Electronic equipment and control method for electronic equipment

ABSTRACT

Portable electronic equipment includes a carried-by-user detector for detecting whether the electronic equipment is in a state carried by a user or not. When the electronic equipment is in a state not carried by the user, i.e., when the user is not employing the electronic equipment, an operating mode is shifted from a normal operating mode to a power saving mode to reduce power consumption of the electronic equipment. Useless consumption of power during non-use of the electronic equipment can be thus reduced. Further, in electronic equipment (timepiece) incorporating a power generator for generating power by converting first energy (motion, pressure or heat) into electric energy as second energy, whether the power generator is generating power, i.e., whether the electronic equipment is carried by the user, is detected by a power generation detecting circuit, and when a non-power-generation time exceeds a predetermined time, the operating mode is shifted to the power saving mode, thereby reducing power consumption. Accordingly, the electronic equipment (timepiece) can be provided with which when the electronic equipment is in the state not carried by the user or when the electronic equipment is in the state not carried by the user and in a state of not generating power, the operating mode of the electronic equipment is shifted to the power saving mode and energy can be saved without inconveniencing the user.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to portable electronic equipment and acontrol method for the electronic equipment, and in particular toelectronic equipment and a control method for the electronic equipmentwith which a power saving mode and a normal operating mode can beswitched over depending on a condition of use of the electronicequipment by the user. More specifically, the present invention relatesto a timepiece and a control method for the timepiece which can indicatethe time with high accuracy for a long time without replacing a battery.

2. Background Art

Recently, small size electronic watches such as wristwatchesincorporating power generators, e.g., solar cells, and operating with noneed of replacing batteries, have been developed as one form ofelectronic equipment. Those electronic watches have a function ofcharging electric power generated by power generators in large-capacitycapacitors, and indicate the time with the power discharged from thecapacitor when power is not generated. The electronic watches cantherefore operate with stability for a long time without batteries. Inconsideration of the inconvenience of replacing batteries and a problemin disposal of exhausted batteries, it is expected that power generatorswill be incorporated in more and more electronic watches in future.

Meanwhile, a power generator incorporated in a wristwatch, etc.comprises a solar cell for converting irradiated light into electricenergy, or a power generating system for converting kinetic energy, e.g.produced upon motion of the user's arm, into electric energy. Such apower generator is very advantageous in utilizing energy in the user'senvironment for conversion into electric energy, but has problems inthat useable energy density is low and energy cannot be obtained incontinuous fashion. Accordingly, power generation can not be performedin a continuous fashion, and the electronic watch operates with thepower accumulated in a large-capacity capacitor while the powergeneration is suspended. For this reason, a large-capacity capacitor isdesired, with a capacity as large as possible. A capacitor having toolarge a size however would raise problems that such a capacitor cannotbe accommodated in a wristwatch device, and a proper level of voltage ishard to obtain because a longer time is required for charging thecapacitor. On the other hand, if the capacity is too small, theelectronic watch would stop operation when power is not generated for along time. Even if the electronic watch is started again by, forexample, irradiating light, the indicated time would be wrong and theprecise time would not be indicated. Thus the electronic watch would notfulfill its function.

In a wristwatch device using a solar cell, because the intensity ofambient illumination can be detected with the solar cell, a system isconceived in which when the illumination intensity lowers below asetting value, the time indication is stopped but the time from whenindication is stopped is continuously counted by an internal counter,and when the illumination intensity rises, the time indication isresumed and the current time is restored based on a value of theinternal counter. With such a wristwatch device, the operation ofindicating the time is stopped and energy is saved when the illuminationis darkened, e.g., while the user is sleeping, and the time indicationis automatically resumed and the current time is restored when itbecomes light, e.g. in the morning. Accordingly, the duration of thelarge-capacity capacitor can be prolonged and the wristwatch can beoperated for a long time without inconveniencing the user. Also, bydesigning a system such that the day-of-time indication is stopped aftera certain period of time has elapsed subsequent to a lowering of theillumination intensity, the time can be continuously indicated even ifthe illumination intensity lowers for a short time as occurs when thewristwatch is hidden under clothes. This system can also save energywithout inconveniencing the user.

However, the user often desires to see the time even during the night,and it is inconvenient if the user cannot know the current timeinstantly on such an occasion. Also, the wristwatch is often not exposedto the sun in the winter during which the user is wearing a coat or thelike. If the time indication is stopped under such a condition, thefunction of the wristwatch is not fulfilled. Conversely, when the userdoes not wear the wristwatch and leaves it in the room, the timeindication continues since the wristwatch is exposed to weak light. Thisresults in wasteful power consumption.

An object of the present invention is therefore to provide electronicequipment and a control method for the electronic equipment with which apower saving mode and a normal operating mode can be switched overdepending on a condition of use of the electronic equipment by the user.

Another object of the present invention is to provide a timepiece and acontrol method for the timepiece which can indicate the time with highaccuracy for a long time without replacing a battery.

DISCLOSURE OF THE INVENTION

To achieve the above objects, the present invention is featured inportable electronic equipment comprising a power supply device capableof accumulating electric energy, a driven device driven with electricpower supplied from the power supply device, a carried-by-user detectorfor detecting whether the electronic equipment is being carried by auser or not, and a mode shift control device for shifting an operatingmode of the driven device from a normal operating mode to a power savingmode in accordance with a detection result of the carried-by-userdetector when the electronic equipment is not carried by the user, tothereby reduce power consumption of the driven device.

Further, the power supply device in the present invention includes apower generator for generating electric power by converting first energyinto the electric energy as second energy, and is able to accumulate thegenerated power.

Further, the carried-by-user detector in the present invention detectswhether the electronic equipment is being carried by the user or not inaccordance with a power generation state of the power generator.

Also, the present invention comprises an operating condition restoringdevice which, when the operating mode is restored to the normal modeagain after a shift to the power saving mode, restores an operatingcondition of the driven device to the same operating condition whichwould have resulted in the case of operating the driven devicecontinuously for a period of time from the shift to the power savingmode to the time of restoring to the normal mode.

Also, the mode shift control device in the present invention shifts theoperating mode to the power saving mode before an amount of poweraccumulated in the power supply device becomes less than a predeterminedamount of power required which is set beforehand and corresponds to theamount of power required for the restoring of the operating condition.

Also, the carried-by-user detector in the present invention detects thecarried state of the electronic equipment based on an electromotivevoltage produced in the power generator.

Also, the carried-by-user detector in the present invention compares anelectromotive voltage produced in the power generator with a pluralityof setting voltage values, and detects the carried state of theelectronic equipment in accordance with a comparison result.

Further, the carried-by-user detector in the present invention detectsthe carried state of the electronic equipment by selecting one of theplurality of setting voltage values depending on the current mode, andcompares the electromotive voltage produced in the power generator withthe selected setting voltage value.

Further, the carried-by-user detector in the present invention sets thesetting voltage value, which is used for determining whether theoperating mode is to be shifted from the power saving mode to the normaloperating mode, to be higher than the setting voltage value used fordetermining whether the operating mode is to be shifted from the normaloperating mode to the power saving mode.

Also, the carried-by-user detector in the present invention detects thecarried state of the electronic equipment based on a charging current inthe power supply device.

Further, the carried-by-user detector in the present invention comparesthe charging current in the power supply device with a plurality ofsetting current values, and detecting the carried state of theelectronic equipment in accordance with a comparison result.

Further, the carried-by-user detector in the present invention detectsthe carried state of the electronic equipment by selecting one of theplurality of setting current values depending on the current mode, andcomparing the charging current in the power supply device with theselected setting current value.

Further, the carried-by-user detector in the present invention sets thesetting current value, which is used for the mode shift from the powersaving mode to the normal operating mode, to be higher than the settingcurrent value used for the shift from the normal operating mode to thepower saving mode.

Also, the carried-by-user detector in the present invention detects thecarried state of the electronic equipment based on a power generationduration time of the power generator.

Further, the carried-by-user detector in the present invention comparesthe power generation duration time of the power generator with aplurality of setting time values, and detecting the carried state of theelectronic equipment in accordance with a comparison result.

Further, the carried-by-user detector in the present invention detectsthe carried state of the electronic equipment by selecting one of theplurality of setting time values depending on the current mode, andcomparing the power generation duration time of the power generator withthe selected setting time value.

Further, the carried-by-user detector in the present invention sets thesetting time value, which is used for the mode shift from the powersaving mode to the normal operating mode, to be longer than the settingtime value used for the shift from the normal operating mode to thepower saving mode.

Also, the carried-by-user detector in the present invention detects thecarried state of the electronic equipment based frequency of the powergenerated by the power generator.

Further, the carried-by-user detector in the present invention detectsthe frequency of the power generated by the power generator by countingthe number of peaks of an electromotive voltage produced in the powergenerator during a period until a setting time elapses from a point intime at which the electromotive voltage has exceeded a setting voltagevalue.

Further, the carried-by-user detector in the present invention comparesthe frequency of the power generated by the power generator with aplurality of setting frequency values, and detects the carried state ofthe electronic equipment in accordance with a comparison result.

Further, the carried-by-user detector in the present invention detectsthe carried state of the electronic equipment by selecting one of theplurality of setting frequency values depending on the current mode, andcompares the frequency of the power generated by the power generatorwith the selected setting frequency value.

Also, the carried-by-user detector in the present invention sets thesetting frequency value, which is used for determining whether theoperating mode is to be shifted from the power saving mode to the normaloperating mode, to be higher than the setting frequency value used fordetermining whether the operating mode is to be shifted from the normaloperating mode to the power saving mode.

Also, the power generator in the present invention includes a pluralityof auxiliary power generators for converting the first energy indifferent forms.

Also, the first energy in the present invention is any of kineticenergy, pressure energy or thermal energy.

Also, the power generator in the present invention generates AC electricpower by converting kinetic energy as the first energy into electricenergy, and the power supply device rectifies and accumulates thegenerated AC power.

Further, the carried-by-user detector in the present invention comprisesswitching means being switched over in accordance with a cycle of the ACpower generated by the power generator, a capacity element foraccumulating electric charges in accordance with the switching operationof the switching means, discharge means inserted in a discharge path ofthe capacity element and discharging the electric charges accumulated inthe capacity element, a measuring portion for counting the powergeneration duration time by measuring a period of time during which avoltage across the capacity element exceeds a predetermined value, and acarried-by-user detecting portion for detecting the carried state of theelectronic equipment based on the power generation duration time.

Also, the carried-by-user detector in the present invention detects thecarried state of the electronic equipment based on the frequency of thepower generated by the power generator.

Further, the carried-by-user detector in the present invention detectsthe frequency of the power generated by the power generator by countingthe number of peaks of an electromotive voltage produced in the powergenerator during a period until a setting time elapses from a point intime at which the electromotive voltage has exceeded a setting voltagevalue.

Further, the carried-by-user detector in the present invention comparesthe frequency of the power generated by the power generator with aplurality of setting frequency values, and detects the carried state ofthe electronic equipment in accordance with a comparison result.

Further, the carried-by-user detector in the present invention detectsthe carried state of the electronic equipment by selecting one of theplurality of setting frequency values depending on the current mode, andcompares the frequency of the power generated by the power generatorwith the selected setting frequency value.

Also, the power generator in the present invention comprises a rotatingweight undergoing swing motion, and a power generation element forgenerating electromotive forces with the rotary motion of the rotatingweight.

Also, the power generator in the present invention comprises a resilientmember to which deformation forces are applied, rotating meansundergoing rotary motion due to restoring forces developed by theresilient member restoring to an original shape, and a power generationelement for generating electromotive forces with the rotary motion ofthe rotating means.

Also, the power generator in the present invention comprises apiezoelectric device for generating electromotive forces with thepiezoelectric effect when subjected to a displacement.

Also, the mode shift control device in the present invention shifts theoperating mode of the driven device to the power saving mode when theelectronic equipment is in the not-carried state and the powergeneration state of the power generator is in a predetermined powergeneration state which is set beforehand and corresponds to the powersaving mode.

Further, the carried-by-user detector in the present invention includesan acceleration sensor for detecting acceleration generated when theelectronic equipment is carried by the user.

Also, the carried-by-user detector in the present invention detects thecarried state of the electronic equipment by detecting a change inelectrode-to-electrode resistance value or electrode-to-electrodecapacitance value occurring when the electronic equipment is carried bythe user.

Also, the carried-by-user detector in the present invention includes aswitch portion turning into an on- or off-state when the electronicequipment is carried by the user, and detects the carried state of theelectronic equipment in accordance with the on/off state of the switchportion.

In addition, the present invention includes a control method forelectronic equipment comprising a power supply device capable ofaccumulating electric energy, and a driven device driven with electricpower supplied from the power supply device, the control methodcomprising a carried-by-user detecting step of detecting whether theelectronic equipment is in a state carried by a user or not, and a modeshift control step of shifting an operating mode of the driven devicefrom a normal operating mode to a power saving mode in accordance with aresult of the detection when the electronic equipment is in a state notcarried by the user, for thereby reducing power consumption of thedriven device.

Further, the power supply device in the present invention includes apower generator for generating electric power by converting first energyinto the electric energy as second energy, and the carried-by-userdetecting step is detects whether the electronic equipment is in thestate carried by the user or not in accordance with a power generationstate of the power generator.

Also, the present invention further comprises an operating conditionrestoring step of, when the operating mode is restored to the normalmode again after a shift to the power saving mode, restoring anoperating condition of the driven device to the same operating conditionwhich would have resulted in the case of operating the driven devicecontinuously for a period of time from the shift to the power savingmode to the time of restoring to the normal mode.

Also, the mode shift control step in the present invention shifts theoperating mode to the power saving mode before an amount of poweraccumulated in the power supply device becomes less than a predeterminedamount of power which is set beforehand and corresponds to the amount ofpower required for the restoring of the operating condition.

Also, the driven device in the present invention is a time indicatingdevice for indicating the time with the electric power supplied from thepower supply device, and the normal operating mode is an indication modecausing the time indicating device to indicate the time.

Also, the first energy in the present invention is any of kineticenergy, pressure energy or thermal energy.

Also, the first energy in the present invention is optical energy, andthe mode shift control step includes the carried-by-user detecting stepof detecting whether the electronic equipment is in the state carried bythe user or not, and shifting the operating mode of the driven device tothe power saving mode when the electronic equipment is in thenot-carried state and the power generation state of the power generatoris in a predetermined power generation state which is set beforehand andcorresponds to the power saving mode.

Also, the driven device in the present invention is a time indicatingdevice for indicating the time with the electric power supplied from thepower supply device, and the mode shift control device shifts theoperating mode of the time indicating device to the power saving mode inaccordance with a power generation state of the power generator, forthereby reducing power consumption of the time indicating device.

Further, the present invention further comprises a time indicationrestoring device for, when the operating mode is restored to a timeindication mode as the normal mode again after a shift to the powersaving mode, restoring a time indicative condition of the timeindicating device to the same time indicative condition which would haveresulted in the case of operating the time indicating devicecontinuously for a period of time from the shift to the power savingmode to the time of restoring to the time indication mode.

Also, the power saving mode in the present invention stops the timeindication in the time indicating device.

Also, the time indicating device in the present invention comprises anhour- and minute-hand driving device for driving hour and minute hands,and a second hand driving device for driving a second hand, and thepower saving mode comprises a first power saving mode in which operationof the second hand driving device is stopped, and a second power savingmode in which operations of the hour- and minute-hand driving device andthe second hand driving device are stopped.

Also, the time indicating device in the present invention is an analogindicating device for mechanically driving analog hands to rotate thehands, and the mode shift control device comprises a power-saving-modetime storage for storing a power-saving-mode duration time during whichthe power saving mode is continued, and a time restoring portion forrestoring the time indication of the analog indicating device based onthe power-saving-mode duration time when the operating mode is shiftedfrom the power saving mode to the indiction mode.

Also, the mode shift control device in the present invention has a modesetting function capable of selectively setting one of the power savingmodes in which the time indication of the time indicating device isstopped in accordance with the power generation state of the powergenerator, and the indication mode in which the time is indicated.

Moreover, the present invention includes a control method for electronicequipment comprising a power supply device capable of accumulatingelectric energy, and a time indicating device capable of indicating thetime with electric power supplied from the power supply device, thecontrol method comprising a carried-by-user detecting step of detectingwhether the electronic equipment is in a state carried by a user or not,and a mode shift control step of shifting an operating mode of thedriven device from a normal operating mode to a power saving mode inaccordance with a detection result in the carried-by-user detecting stepwhen the electronic equipment is in a state not carried with the user,for thereby reducing power consumption of the driven device.

Further, the power supply device in the present invention includes apower generator for generating electric power by converting first energyinto the electric energy as second energy, and the carried-by-userdetecting step detects whether the electronic equipment is in the statecarried with the user or not in accordance with a power generation stateof the power generator.

Also, the present invention further comprises a time indicationrestoring step of, when the operating mode is restored to the normalmode again after a shift to the power saving mode, restoring a timeindicative condition of the time indicating device to the same timeindicative condition as would have resulted in the case of operating thetime indicating device continuously for a period of time from the shiftto the power saving mode to the time of restoring to the normal mode.

Also, the mode shift control step in the present invention shifts theoperating mode to the power saving mode before an amount of poweraccumulated in the power supply device becomes less than a predeterminedamount of power which is set beforehand and corresponds to the amount ofpower required for the restoring of the operating condition.

Also, the mode shift control step in the present invention includes apower-generation-state determining step of determining whether the powergenerator is in a state of generating power or not based on whether anelectromotive voltage of the power generator is higher than a settingvoltage set beforehand, and shifting the operating mode from the powersaving mode to an indication mode, in which the time is indicated, inaccordance with a result of the determination when the power generatoris brought into the state of generating power.

Also, the mode shift control step in the present invention includes apower-generation-state determining step of determining whether the powergenerator is in a state of generating power or not based on whether apower generation duration time of the power generator is longer than asetting time set beforehand, and shifts the operating mode from thepower saving mode to an indication mode, in which the time is indicated,in accordance with a result of the determination when the powergenerator is brought into the state of generating power.

Also, the power saving mode in the present invention stops the timeindication in the time indicating device.

Also, the time indicating device in the present invention comprises anhour- and minute-hand driving device for driving hour and minute hands,and a second hand driving device for driving a second hand, and thepower saving mode comprises a first power saving mode in which operationof the second hand driving device is stopped, and a second power savingmode in which operations of the hour- and minute-hand driving device andthe second hand driving device are stopped.

According to any of the above-described features of the presentinvention, when the electronic equipment is not carried by the user, orwhen the electronic is not carried by the user and the power generatoris in the state of not generating power, the operating mode is shiftedto the power saving mode. The electronic equipment (timepiece) isprovided which can save energy without inconveniencing the user.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a construction of a timepieceaccording to a first embodiment and containing a motor and a powergenerator.

FIG. 2 shows, in the form of a schematic block diagram, a constructionof the timepiece shown in FIG. 1.

FIG. 3 is a flowchart showing a summary of a mode changing process inthe timepiece shown in FIG. 1.

FIG. 4 is a schematic diagram showing a construction of a timepieceaccording to a second embodiment.

FIG. 5 is a functional block diagram showing a construction of a controlunit and related components according to the second embodiment.

FIG. 6 is a circuit diagram of a power-generation-state detectingportion according to the second embodiment.

FIGS. 7a-7 c are timing charts for explaining the operation of a firstdetecting circuit according to the second embodiment.

FIGS. 8a-8 f are timing charts for explaining the operation of a seconddetecting circuit according to the second embodiment.

FIGS. 9a-9 b conceptual views for explaining an electromotive voltageproduced depending on a difference in rotational speed of a powergenerating rotor and the relation of a detection signal with respect tothe electromotive voltage in the second embodiment.

FIG. 10 is a flowchart showing a summary of a mode setting step in thetimepiece according to the second embodiment.

FIG. 11 is a block diagram showing a construction of apower-generation-state detecting portion according to a modification ofthe second embodiment.

FIG. 12 is a block diagram of a power-generation-state detecting portionaccording to a third embodiment of the present invention.

FIGS. 13a-13 c are timing charts of the power-generation-state detectingportion according to the third embodiment.

FIG. 14 shows, in the form of a schematic block diagram, a constructionof a timepiece according to a fourth embodiment of the presentinvention.

DETAILED DESCRIPTION

The present invention will be described below in more detail withreference to the drawings.

[1] First Embodiment

[1.1] Construction of Timepiece

FIG. 1 schematically shows a construction of a timepiece 1 as one formof electronic equipment according to the first embodiment of the presentinvention.

In the timepiece 1 of the first embodiment, a stepping motor 10 isdriven by a control device 20 to stepwisely rotate a second hand 61, aminute hand 62, and an hour hand 63 through a wheel train 50. Electricpower for driving the stepping motor 10, the control device 20, etc. isproduced by a power generator 40.

The power generator 40 for the timepiece 1 comprises an AC powergenerator of electromagnetic induction type wherein a power generatingrotor 43 is rotated within a power generating stator 42 to induceelectric power in a power generating coil 44 connected to the powergenerating stator 42, the induced power being outputted to the outside.Further, in the timepiece 1 of this embodiment, a rotating weight 45 isemployed as a means for transmitting kinetic energy to the powergenerating rotor 43, and motion of the rotating weight 45 is transmittedto the power generating rotor 43 through a speed-up gear 46. In the caseof the timepiece 1 being of wristwatch type, the rotating weight 45swings in the timepiece 1 with movement of the user's arm, for example.Thus, electric power can be generated by utilizing energy in the naturalenvironment of the user, and the timepiece 1 can be driven with thegenerated power.

The power outputted from the power generator 40 is subjected tohalf-wave rectification by a diode 47, and thereafter once accumulatedin a large-capacity capacitor 48 which serves as a power supply device.Then, driving power for driving the stepping motor 10 is supplied fromthe large-capacity capacitor 48 to a driving circuit 30 in the controldevice 20 through a voltage stepping-up and -down circuit 49. Thevoltage stepping-up and -down circuit 49 in this embodiment comprises aplurality of capacitors 49 a, 49 b and 49 c for increasing or reducing avoltage in multiple steps. The voltage supplied to the driving circuit30 can be adjusted by a control signal φ11 from a control circuit 23 inthe control device 20. Also, the output voltage of the voltagestepping-up and -down circuit 49 is supplied to the control circuit 23through a monitoring circuit φ12. With such a circuit arrangement, theoutput voltage can be monitored, and the control device 20 can determinewhether the power generator 40 is generating power or not based on asmall increase or decrease of the output voltage.

The stepping motor 10 used in the timepiece 1 of this first embodimentis a motor driven with a pulse signal. Such a motor is called a pulsemotor, a stepping motor, a step-rotating motor or a digital motor, andis employed as an actuator for a digital control device in many cases.Recently, stepping motors having smaller size and weight have beenemployed as actuators for many electronic devices or informationequipment which are small in size and are suitable for being carried byusers. Typical examples of these electronic devices are timepieces suchas electronic watches, time switches, and chronographs. The steppingmotor 10 in this embodiment is of PM type (permanent magnet rotatingtype) comprising a driving coil 11 for generating magnetic forces withdriving pulses supplied from the control device 20, a stator 12 excitedby the driving coil 11, and a rotor 13 rotating under a magnetic fieldproduced within the stator 12, the rotor 13 being constructed of adisk-shaped double-pole permanent magnet. Magnetic saturation portions17 are provided in the stator 12 so that the magnetic forces generatedby the driving coil 11 produce different magnetic poles in respectivephases (poles) 15 and 16 around the rotor 13. Also, for restricting thedirection of rotation of the rotor 13, an inner notch 18 is formed in anappropriate position along an inner periphery of the stator 12 togenerate cogging torque, thereby stopping the rotor 13 in an appropriateposition.

The rotation of the rotor 13 of the stepping motor 10 is transmitted torespective hands by a wheel train 50 which comprises a 5th wheel 51meshing with the rotor 13 through a pinion, a 4th (secondhand) wheel 52,a 3rd wheel 53, a 2nd (center) wheel 54, a minute wheel 55 and an hourwheel 56. A second hand 61 is connected to a shaft of the 4th wheel 52,a minute hand 62 is connected to a shaft of the 2nd wheel 54, and anhour hand 63 is connected to a shaft of the hour wheel 56. With therotation of the rotor 13, those hands are rotated to indicate the time.Of course, a transmission system (not shown) for indicating a date, etc.can also be connected to the wheel train 50.

In the timepiece 1, to indicate the time with the rotation of thestepping motor 10, driving pulses are supplied to the stepping motor 10while counting (clocking) a signal having a reference frequency. Thecontrol device 20 for controlling the stepping motor 10 in thisembodiment comprises a pulse synthesis circuit 22 for generatingreference pulses of the reference frequency and pulse signals differentin pulse width and timing by using a reference oscillation source 21such as a quartz oscillator, and a control circuit 23 for controllingthe stepping motor 10 in accordance with the various pulse signalssupplied from the pulse synthesis circuit 22. Though described later indetail, the control circuit 23 controls the driving circuit and detectsthe rotation, and is designed to be able to output pulses such asdriving pulses supplied to the driving coil 11 through the drivingcircuit for driving the driving rotor 13 of the stepping motor 10,rotation detecting pulses supplied subsequent to the driving pulses toinduce an induction voltage for detecting the rotation of the drivingrotor 13, auxiliary pulses having large effective power to forciblyrotate the driving rotor 13 when it is not rotated, and demagnetizingpulses having different magnetic poles and supplied subsequent to theauxiliary pulses for demagnetization.

The driving circuit 30 for supplying various driving pulses to thestepping motor 10 under control of the control circuit 23 comprises abridge circuit made up of a p-channel MOS transistor 33 a and ann-channel MOS transistor 32 a which are connected in series, a p-channelMOS transistor 33 b, and an n-channel MOS transistor 32 b. This circuitarrangement makes it possible to control the power supplied to thestepping motor 10 from the large-capacity capacitor 48, as the powersupply device, and the voltage stepping-up and -down circuit 49. Thedriving circuit 30 further comprises rotation detecting resistors 35 aand 35 b connected respectively to the p-channel MOS transistors 33 aand 33 b in parallel, and p-channel MOS transistors 34 a and 34 b forsupplying chopper pulses to the resistors 35 a and 35 b for the purposeof sampling. By applying control pulses, which are different in polarityand pulse width, at the respective timings from the control circuit 23to gate electrodes of these MOS transistors 32 a, 32 b, 33 a, 33 b, 34 aand 34 b, therefore, the driving pulses having different polarities canbe supplied to the driving coil 11, or the detecting pulses fordetecting the rotation of the rotor 13 and for exciting the inducedvoltage to detect a magnetic field can be supplied.

[1.2] Functional Construction of Timepiece of First Embodiment

FIG. 2 shows, in the form of a functional schematic block diagram, aconstruction of the timepiece 1 of the first embodiment.

In the timepiece 1 of this embodiment, as described above, a referencesignal produced by the pulse synthesis circuit 22 is supplied to adriving control circuit 24, and the driving circuit 30 is operated undercontrol of the driving control circuit 24 to drive the stepping motor 10for rotating the hands in a stepwise manner.

Power is supplied to the control circuit 23 and the driving circuit 30from the power supply device 48, and the power supply device 48 ischarged with the power generated by the power generator 40. A voltage(electromotive voltage) Vgen on the output side of the power generator40 is supplied to a power generation detecting circuit 91 in a modesetting section 90 of the control circuit 23, and the power generationdetecting circuit 91 is able to determine whether power is generated bythe power generator 40. The power generation detecting circuit 91 inthis embodiment comprises a first detecting circuit 97 for comparing theelectromotive voltage Vgen with a setting value Vo and then determiningwhether power generation is detected, and a second detecting circuit 98for comparing power generation duration time Tgen, during which theelectromotive voltage Vgen not lower than a voltage Vbas fairly smallerthan the setting value Vo is obtained, with a setting value To and thendetermining whether power generation is detected. If any one of theconditions determined by the first and second detecting circuits 97 and98 is satisfied, the power generation detecting circuit 91 determinesthat power generation is detected.

The mode setting section 90 further includes a voltage detecting circuit92 capable of comparing an output voltage Vout of the large-capacitycapacitor 48 as the power supply device with a setting value, and thendetermining a charged state of the large-capacity capacitor 48.Determination results from the power generation detecting circuit 91 andthe voltage detecting circuit 92 are supplied to a central controlcircuit 93 having functions to control the mode setting section 90 andother components of the control circuit 23 for selectively setting oneof a power saving mode to reduce power consumption and an indicationmode to perform normal indication of the time.

In this connection, the power saving mode means an operating mode inwhich the driving of the stepping motor 10 is stopped and the stepwiserotation of the hands is stopped. In such a condition, however, thereference oscillation source 21, the pulse synthesis circuit 22, thevoltage detecting circuit 92, the mode setting section 90, etc. are keptin an operative state so that the operating mode can be switched over.

The central control circuit 93 includes a non-power-generation timemeasuring circuit 99 for measuring a non-power-generation time Tn duringwhich power generation is not detected by the first and second detectingcircuits 97 and 98. When the non-power-generation time Tn exceeds apredetermined setting time, the operating mode shifts from theindication mode to the power saving mode. The set operating mode isstored in a mode storage 94, and the stored information is supplied tothe driving control circuit 24, a time information storage 96, and asetting value changing portion 95. Upon the shift from the indicationmode to the power saving mode, the driving control circuit 24 stopssupply of the pulse signal to the driving circuit 30, thereby stoppingthe driving circuit 30. Accordingly, the motor 10 ceases rotation andthe time indication is stopped.

Also, upon the shift from the indication mode to the power saving mode,the time information storage 96 starts operation as a suspension timecounter which receives the reference signal produced by the pulsesynthesis circuit 22 and stores a duration time of the power savingmode. Then, upon the shift from the power saving mode to the indicationmode, the time information storage 96 effects another function ofcounting fast-forward pulses supplied from the driving control circuit24 to the driving circuit 30 and causing the resumed time indication tobe restored to the current time.

The setting value changing portion 95 changes magnitudes of the settingvalues Vo and To of the first and second detecting circuits 97 and 98 inthe power generation detecting circuit 91 upon the shift from the powersaving mode to the indication mode. In this embodiment, setting valuesVa and Ta in the indication mode are set to be lower than setting valuesVb and Th in the power saving mode. In the indication mode, therefore,the accuracy in detecting the power generation state is set to be higher(i.e., more sensitive or distinct). Thus, even with the voltage beinglow or the power generation duration time being short, if a powergeneration output is obtained, it is determined that power generation isdetected, and the indication mode is maintained. On the other hand, inthe power saving condition, the accuracy in detecting the powergeneration state is set to be lower (i.e., more insensitive orindistinct). Thus, when the relatively high electromotive voltage isobtained, or when the relatively long power generation duration time isobtained, it is determined that power generation is detected. Further,if the condition is satisfied that the charged voltage is sufficient,the operating mode shifts to the indication mode.

Since the system supply voltage varies depending on the charged state,it is desired to generate the setting voltage used for comparison anddetermination of the electromotive voltage Vgen, etc. by using aconstant-voltage circuit which generates a stable voltage. Also, it ispossible to employ, as a threshold (setting value), a voltage having afixed difference with respect to the varying system source voltage. Thefixed difference value can be determined, for example, by using athreshold Vth of a MOSFET which does not depend on the power supplyvoltage.

[1.3] Mode Setting Steps

FIG. 3 shows, in the form of a flowchart, a summary of mode settingsteps for carrying out a mode changing process in the timepiece of thisembodiment.

First, the current operating mode is determined in step 71.

If the current operating mode is the power saving mode, counting of thesuspension time is continued by the time information storage 96 in step74. Then, the setting values Vo and To in the power generation detectingcircuit 91 are set to the values Vb and Tb for the power saving mode instep 75. On the other hand, if the current operating mode is theindication mode, the driving control circuit 24 controls the drivingcircuit 30 to produce the driving pulses and effects the time indicationin step 72. Then, the setting values Vo and To in the power generationdetecting circuit 91 are set to the values Va and Ta for the indicationmode in step 73.

Next, a power generation level (electromotive voltage) is detected instep 76.

If it is determined in step 76 that the electromotive voltage isproduced even though its level is small, the power generation durationtime Tgen is counted up in step 77.

Then, the power generation duration time Tgen is compared with thesetting time To in step 78. If the power generation duration time Tgenis not less than the setting time To, processing goes to step 80 upon adecision that power generation is detected.

If it is determined in step 78 that the power generation duration timeTgen does not reach the setting time To, the electromotive voltage Vgenis compared with the setting value Vo in step 79. If the electromotivevoltage Vgen reaches the setting value Vo, processing goes to step 80upon a decision that power generation is detected.

In step 80, the mode is determined again. If the mode is not the powersaving mode, the non-power-generation time Tn is cleared in step 81,following which processing returns to step 71 and continues the timeindication in step 72.

Conversely, if the mode is the power saving mode, the voltage Vout ofthe power supply device 48 is determined in step 82. If the power supplydevice 48 is sufficiently charged, the mode is shifted from the powersaving mode to the indication mode and the power saving mode is clearedin step 83.

If the power supply device 48 is not sufficiently charged as a result ofdetermining the voltage Vout of the power supply device 48 in step 82,processing returns to step 71 again while the power saving mode ismaintained, followed by repeating the process described above.

When the time is indicated again upon the shift to the indication mode,the time indication is fast forwarded in accordance with the suspensiontime counted by the time information storage 96, and normal rotation ofthe hands per second is started after restoring to the current time. Asa result, the user can view the precise time indicated after returningto the indication mode.

On the other hand, if the electromotive voltage is not detected in step76, or if the power generation duration time Tgen does not reach thesetting time To and the electromotive voltage Vgen also does not reachthe setting value Vo, processing goes to step 85 upon a decision thatpower generation is not detected, where the mode at that time isdetermined. In this respect, when the electromotive voltage is notdetected in step 76, the power generation duration time Tgen is clearedin step 84.

If the mode is determined to be the power saving mode in step 85,processing returns to step 71 directly to continue counting-up of thesuspension time.

If the mode is determined to be the indication mode, thenon-power-generation time Tn is counted up in step 86, and whether apredetermined non-power-generation time is continued or not isdetermined in step 87. If the non-power-generation time Tn has elapsed,the mode is shifted from the indication mode to the power saving mode instep 88, thereby starting the power saving. In step 88, the operationsof both the driving control circuit 24 and the driving circuit 30 arestopped to nullify power consumption of the motor 10, and counting ofthe suspension time is started by the time information storage 96.

Thus, in the timepiece 1 of this embodiment, the time indication isstopped or resumed depending on whether power is generated or not. Asdescribed above, the power generator 40 in this embodiment is such asystem that power is generated by motion of the user's arm or vibrationwith the aid of the rotating weight 45. Accordingly, the fact that powergeneration is detected means that the timepiece is fitted on the user'sarm, or that the user carries the timepiece while putting it in a pocketor the like. In view of the above, when power generation is detected,the mode is shifted to the indication mode in which the time isindicated, upon a decision that the timepiece is carried by the user.Conversely, when power generation is not detected, the mode is shiftedto the power saving mode in which the time is not indicated, upon adecision that the timepiece is not carried by the user. As a result, theenergy accumulated in the large-capacity capacitor 48 can be saved.

Further, in the timepiece 1 of the first embodiment, it is determinedthat power generation is detected, when the predetermined electromotivevoltage Vgen is detected, and when power generation is continued for thepredetermined time. Therefore, even when the mode is shifted to thepower saving mode in a condition of the timepiece not being carried bythe user and power generation is then accidentally induced for somereason, e.g., vibration, the mode is kept from shifting to theindication mode if the electromotive voltage is weak and the durationtime is short. Useless consumption of energy can be thus prevented. Onthe other hand, in the indication mode, since the setting value Vo isset to be lower than in the power saving mode, it is determined thatpower generation is detected if the electromotive voltage is obtainedeven though the detected electromotive voltage Vgen is somewhat low. Asa result, the time indication is continued so long as power is generatedeven at a low level. Also, in the indication mode, since the settingtime To for the power generation duration time Tgen is also set to beshorter, the time indication is maintained so long as power is generatedeven for a short time.

Moreover, in the timepiece 1 of the first embodiment, thenon-power-generation time Tn is measured, and the mode is not shifted tothe power saving mode unless the non-power-generation time reaches thesetting time. Accordingly, it is possible to maintain the timeindication not only in the case where motion of the user is stopped andpower is not generated for a short time, but also in the case where theuser takes off the wristwatch for a period of time such as during ameeting. Also, the time may be continuously indicated even when the usertakes off the wristwatch all night. As an alternative, for the purposeof saving energy, the mode may be shifted to the power saving mode ifthe user takes off the wristwatch for a period of about five minutes.

[1.4] Advantages of First Embodiment

With the timepiece 1 of this embodiment, as described above, whether thetimepiece is carried by the user or not can be automatically determinedbased on the power generation state. Then, the timepiece cansufficiently function as a wristwatch or the like by indicating the timewhen carried by the user, and can reduce consumption of energy withoutindicating the time when not carried by the user.

More specifically, when the hands are fast forwarded with shortenedintervals of hand rotation for restoring the time indication to thecurrent time, power consumption is increased in comparison with that inthe indication mode (i.e., the normal operating mode).

However, when the above-described analog watch is used as the timepiece1 and is operated with a 12-hour indication scheme, the hands take thesame position each period of 12 hours. Accordingly, as the elapsed timein the power saving mode is prolonged, the power saving effect isincreased and energy consumption can be reduced more effectively. Thisis equally applied to the case where the timepiece is operated with a24-hour indication scheme and repeats the same indication state at aperiod of 24 hours.

To describe in more detail, assuming, for example, that power of about X[W] is consumed when the hands are driven in the indication mode for 12hours, the power required for driving the hands for 108 hours (12×9hours) is about (X×9) [W].

By contrast, assuming, for example, that power of about Y (>X) [W] isconsumed when the timepiece is left standing in the power saving modefor 12 hours and then restored to the current time, the power requiredfor restoring the hands to the current time after being left standingfor 108 hours is also Y [W]. Thus, the longer a period of time duringwhich the timepiece is left standing in the power saving mode, thehigher is the power saving effect.

Accordingly, the power once charged in the large-capacity capacitor canbe effectively utilized. Even with the timepiece left standing for along time, the time is not indicated and only the elapsed time ismeasured during such a period of time. When the user wears the timepieceagain, the time indication is resumed and restored to the current time,thereby indicating the precise time. With no need of employing acapacitor being so large in capacity, therefore, a small size wristwatchor the like capable of keeping time for a long time with good accuracycan be realized by incorporating, in place of a battery, a powergenerator and a capacitor having an appropriate capacity. Also, sincethe capacity of a capacitor is not required to be so large, a timepiececan be realized which has a good start-up characteristic, and can resumethe indication and restore to the current time as soon as powergeneration is started. In addition, with the timepiece of thisembodiment, the user can always see the time regardless of surroundingconditions even in a dark place, for example, when carried by the user,and therefore the user is completely free from inconvenience.

[1.5] Modifications of First Embodiment

[1.5.1] First Modification

While the above description has been made in connection with, by way ofexample, the timepiece indicating the time with the motor 10, thepresent invention is of course also applicable to another type oftimepiece indicating the time with an LCD (Liquid Crystal Device), etc.In this modification, the time can be continuously counted for a longtime while saving power consumed by the LCD, and the precise currenttime can be always displayed as required.

[1.5.2] Second Modification

Further, the above description has been made as employing the powergeneration detecting circuit 91 which includes both the first detectingcircuit 97 for comparing the electromotive voltage Vgen with the settingvalue Vo and then determining whether power generation is detected, andthe second detecting circuit 98 for comparing the power generationduration time Tgen, during which the electromotive voltage Vgen notlower than the voltage Vbas fairly smaller than the setting value Vo isobtained, with the setting value To and then determining whether powergeneration is detected. However, whether power is generated or not canbe of course also determined by using one of the first and seconddetecting circuits 97 and 98.

By providing the second detecting circuit 98, in particular, whether theuser wears the timepiece or not can be determined with higherreliability.

[1.5.3] Third Modification

In the above description, as shown in FIG. 3, when the mode is in theindication mode, whether the predetermined non-power-generation time iscontinued or not is determined in step 87. If the countednon-power-generation time Tn has elapsed, the mode is shifted from theindication mode to the power saving mode, thereby starting the powersaving. By contrast, in this third modification, the shift to the powersaving mode is allowed only when the voltage of the large-capacitycapacitor 48 as the power supply device is not less than a voltagesufficient for restoring the indication of the current time at the timeof the shift from the power saving mode to the indication mode.

More specifically, even if the counted non-power-generation time Tnexceeds the predetermined non-power-generation time, it is determinedwhether the voltage of the large-capacity capacitor 48 is not less thanthe voltage sufficient for restoring the time indication (high-speedhand rotation to the current time) at the time of return to theindication mode. Then, the mode is shifted to the power saving mode ifthe capacitor voltage is not less than the voltage sufficient forrestoring the indication of the current time at the time of return tothe indication mode.

On the other hand, if the voltage of the large-capacity capacitor 48 isless than the voltage sufficient for restoring the indication of thecurrent time at the time of return to the indication mode, the timeindication, i.e., the indication mode, is continued in an indicationmode to prompt the user to charge the capacitor.

In this case, the indication mode for prompting the user to charge thecapacitor is realized by setting intervals of hand rotation to twoseconds, for example, when intervals of second-hand rotation are set toone second under normal hand driving.

As a result of the above construction, the user can easily understandthat charging is not sufficient, and can forcibly charge the capacitorby forcibly shaking the timepiece.

[1.5.4] Fourth Modification

In the above description, as shown in FIG. 3, the voltage Vout of thepower supply device 48 is determined in step 82, and if the capacitor isnot sufficiently charged, the power saving mode is maintained. Bycontrast, in this fourth modification, when the power supply device 48is not sufficiently charged and the voltage Vout of the power supplydevice 48 is a voltage that is insufficient for restoring the indicationof the current time, but sufficient for performing the normal handdriving, the normal hand driving is resumed without restoring theindication of the current time.

As a result, because the normal hand driving is started, but theindication of the current time is not restored, the user can easilyunderstand that charging is not sufficient, and can forcibly charge thecapacitor by forcibly shaking the timepiece.

[2] Second Embodiment

Next, a second embodiment according to the present invention will bedescribed with reference to the drawings.

[2.1] Entire Construction

FIG. 4 shows a schematic construction of a timepiece 1 according to thesecond embodiment. In FIG. 4, similar components to those in the firstembodiment of FIG. 1 are denoted by the same numerals.

The timepiece 1 is a wristwatch, and when used, the user winds aroundthe wrist a band coupled to a timepiece body. The timepiece 1 of thisembodiment mainly comprises a power generation unit A for generating ACpower, a power supply unit B for rectifying an AC voltage from the powergeneration unit A, accumulating the stepped-up voltage and supplyingpower to the associated components, a control unit C for detecting apower generation state of the power generation unit A (in apower-generation-state detecting portion 91 described later) andcontrolling the entirety of the timepiece in accordance with a detectionresult, a hand rotating mechanism D for rotating hands stepwise by usinga stepping motor 10, and a driving unit E for driving the hand operatingmechanism D in accordance with a control signal from the control unit C.The control unit C switches over an operating mode depending on thepower generation state of the power generation unit A between anindication mode in which the hand operating mechanism D is driven toindicate the time, and a power saving mode in which supply of power tothe hand rotating mechanism D is stopped for saving of power. Also, theshift from the power saving mode to the indication mode is forcibly madeby the user holding the timepiece 1 in the hand and shaking it.

Those units will be described one by one below, but the control unit Cwill be described last with reference to a functional block diagram.

[2.1.1] Power Generation Unit

The power generation unit A will be first described.

The power generation unit A comprises a power generator 40, a rotatingweight 45 and a speed-up gear 46.

The power generator 40 comprises an AC power generator ofelectromagnetic induction type wherein a power generating rotor 43 isrotated within a power generating stator 42 to induce electric power ina power generating coil 44 connected to the power generating stator 42,the induced power being outputted to the outside. Also, the rotatingweight 45 functions as a means for transmitting kinetic energy to thepower generating rotor 43. Then, motion of the rotating weight 45 istransmitted to the power generating rotor 43 through the speed-up gear46. In the case of the timepiece 1 being of wristwatch type, therotating weight 45 swings in the timepiece 1 with movement of the user'sarm, for example,. Thus, electric power can be generated by utilizingenergy in the natural environment of the user, and the timepiece 1 canbe driven with the generated power.

[2.1.2] Power Supply Unit

Next, the power supply unit B will be described.

The power supply unit B comprises a diode 47 acting as a rectifyingcircuit, a large-capacity capacitor 48, and a voltage stepping-up and-down circuit 49. The voltage stepping-up and -down circuit 49 comprisesa plurality of capacitors 49 a, 49 b and 49 c for increasing andreducing a voltage in multiple steps. The voltage supplied to thedriving unit E can be adjusted by a control signal φ11 from the controlunit C. Also, the output voltage of the voltage stepping-up and -downcircuit 49 is supplied to the control unit C with a monitoring signalφ12 so that the output voltage can be monitored. Here, the power supplyunit B takes Vdd (higher voltage side) as a reference potential (GND),and produces Vss (lower voltage side) as a supply source voltage.

[2.1.3] Hand Rotating Mechanism

Next, the hand rotating mechanism D will be described.

The stepping motor 10 used in the hand rotating mechanism D is a motordriven with a pulse signal. Such a motor is called a pulse motor, astepping motor, a step-rotating motor or a digital motor, and isemployed as an actuator for a digital control device in many cases.Recently, stepping motors having smaller size and weight have beenemployed as actuators for many electronic devices or informationequipment which are small in size and are suitable for being carried byusers. Typical examples of these electronic devices are timepieces suchas electronic watches, time switches, and chronographs.

[2.1.3.1] Stepping Motor

The stepping motor 10 in this second embodiment comprises a driving coil11 for generating magnetic forces with driving pulses supplied from thedriving unit E, a stator 12 excited by the driving coil 11, and a rotor13 rotating under a magnetic field produced within the stator 12. Also,the stepping motor 10 is of PM type (permanent magnet rotating type)wherein the rotor 13 is constructed of a disk-shaped double-polepermanent magnet. Magnetic saturation portions 17 are provided in thestator 12 so that the magnetic forces generated by the driving coil 11produce different magnetic poles in respective phases (poles) 15 and 16around the rotor 13. Further, for restricting the direction of rotationof the rotor 13, an inner notch 18 is formed in an appropriate positionalong an inner periphery of the stator 12 to generate cogging torque,thereby stopping the rotor 13 in an appropriate position.

The rotation of the rotor 13 of the stepping motor 10 is transmitted torespective hands by a wheel train 50 which comprises a 5th wheel 51meshing with the rotor 13 through a pinion, a 4th (secondhand) wheel 52,a 3rd wheel 53, a 2nd (center) wheel 54, a minute wheel 55 and an hourwheel 56. A second hand 61 is connected to a shaft of the 4th wheel 52,a minute hand 62 is connected to a shaft of the 2nd wheel 54, and anhour hand 63 is connected to a shaft of the hour wheel 56. With therotation of the rotor 13, those hands are rotated to indicate the time.Of course, a transmission system (not shown) for indicating a date, etc.can also be connected to the wheel train 50.

[2.1.4] Driving Unit

Next, the driving unit E supplies various driving pulses to the steppingmotor 10 under control of the control unit C. The driving unit Ecomprises a bridge circuit made up of a p-channel MOS transistor 33 aand an n-channel MOS transistor 32 a which are connected in series, ap-channel MOS transistor 33 b, and an n-channel MOS transistor 32 b. Thedriving unit E further comprises rotation detecting resistors 35 a and35 b connected respectively to the p-channel MOS transistors 33 a and 33b in parallel, and p-channel MOS transistor 34 a and 34 b for supplyingchopper pulses to the resistors 35 a and 35 b for the purpose ofsampling. By applying control pulses, which are different in polarityand pulse width, at the respective timings from the control unit C togate electrodes of those MOS transistors 32 a, 32 b, 33 a, 33 b, 34 aand 34 b, therefore, the driving pulses having different polarities canbe supplied to the driving coil 11, or the detecting pulses fordetecting the rotation of the rotor 13 and for exciting the inducedvoltage to detect a magnetic field can be supplied.

[2.1.5] Control Unit

Next, the construction of the control unit C will be described withreference to FIG. 5. FIG. 5 is a functional block diagram of the controlunit C and related components. The control unit C comprises a pulsesynthesis circuit 22, a mode setting section 90, a time informationstorage 96, and a driving control circuit 24.

First, the pulse synthesis circuit 22 is made up of an oscillationcircuit for oscillating reference pulses of stable frequency by using areference oscillation source 21 such as a quartz oscillator, and asynthesis circuit for synthesizing frequency-divided pulses, obtained byfrequency division of the reference pulse, and the reference pulse toproduce various pulse signals which are different in pulse width andtiming.

Then, the mode setting section 90 is made up of a power-generation-statedetecting portion 91, a setting value changing portion 95 for changingsetting values employed to detect the power generation state, a voltagedetecting circuit 92 for detecting a charged voltage Vc of thelarge-capacity capacitor 48, a central control circuit 93 forcontrolling a time indication mode depending on the power generationstate and controlling a voltage step-up factor based on the chargedvoltage, and a mode storage 94 for storing the mode.

The power-generation-state detecting portion 91 comprises a firstdetecting circuit 97 for comparing an electromotive voltage Vgen of thepower generator 40 with a setting voltage value Vo and then determiningwhether power generation is detected, and a second detecting circuit 98for comparing a power generation duration time Tgen, during which theelectromotive voltage Vgen not lower than a setting voltage value Vbasfairly smaller than the setting voltage value Vo is obtained, with asetting time value To and then determining whether power generation isdetected. If any one of the conditions determined by the first andsecond detecting circuits 97 and 98 is satisfied, thepower-generation-state detecting portion 91 determines that powergeneration is detected. In this connection, the setting voltage valuesVo and Vbas are each a negative voltage with Vdd (=GND) as a reference,and represents a potential difference from Vdd. Constructions of thefirst and second detecting circuits 97 and 98 will be described later.

Here, the setting voltage value Vo and the setting time value To can becontrolled to change selectively by the setting value changing portion95. Upon the shift from an indication mode to a power saving mode, thesetting value changing portion 95 changes the magnitudes of the settingvalues Vo and To of the first and second detecting circuits 97 and 98 inthe power generation state detecting portion 91. In this embodiment,setting values Va and Ta in the indication mode are set to be lower thansetting values Vb and Tb in the power saving mode. Therefore, the shiftfrom the power saving mode to the indication mode requires large powerto be generated. A required level of the generated power is not enoughat such a level as generated when the timepiece 1 is usually carriedwith the user, but must be such a high level as generated when the usertries to forcibly charge the capacitor by shaking their wrist. In otherwords, the setting values Vb and Th in the power saving mode are set tobe able to detect forcible charging.

Further, the central control circuit 93 includes a non-power-generationtime measuring circuit 99 for measuring a non-power-generation time Tnduring which power generation is not detected by the first and seconddetecting circuits 97 and 98. When the non-power-generation time Tnexceeds a predetermined setting time, the operating mode shifts from theindication mode to the power saving mode. Conversely, the shift from thepower saving mode to the indication mode is effected when the followingconditions are satisfied; that the power generation unit A is in thestate of generating power as detected by the power-generation-statedetecting portion 91, and the charged voltage VC of the large-capacitycapacitor 48 is sufficient.

Since the power supply unit B in this embodiment includes the voltagestepping-up and -down circuit 49, the hand rotating mechanism D can bedriven by boosting the supply source voltage with the voltagestepping-up and -down circuit 49 even when the charged voltage VC is ina relatively low condition. Thus the central control circuit 93determines the voltage step-up factor based on the charged voltage VCand controls the voltage stepping-up and -down circuit 49.

However, if the charged voltage VC is too low, the supply source voltagecapable of operating the hand rotating mechanism D cannot be obtainedeven after being stepped up. If the mode is shifted from the powersaving mode to the indication mode in such a case, the precise timeindication cannot be achieved and extra power is consumed.

Taking into account the above point, in this embodiment, the chargedvoltage VC is compared with a setting voltage value Vc set beforehand,to thereby determine that the charged voltage VC is sufficient.Satisfaction of this determination is one additional condition forallowing the shift from the power saving mode to the indication mode.

The thus-set mode is stored in the mode storage 94, and the storedinformation is supplied to the driving control circuit 24, the timeinformation storage 96, and the setting value changing portion 95. Uponthe shift from the indication mode to the power saving mode, the drivingcontrol circuit 24 stops supply of the pulse signal to the driving unitE, thereby stopping the operation of the driving unit E. Accordingly,the motor 10 ceases rotation and the time indication is stopped.

Next, the time information storage 96 is made up of a counter and amemory (though not shown). The time information storage 96 receives thereference signal produced by the pulse synthesis circuit 22 and startstime counting upon the shift from the indication mode to the powersaving mode, and finishes the time counting upon the shift from thepower saving mode to the indication mode. As a result, a duration timeduring which the power saving mode is maintained is measured. Theduration time of the power saving mode is stored in the memory. Further,upon the shift from the power saving mode to the indication mode, thetime information storage 96 counts fast-forward pulses supplied from thedriving control circuit 24 to the driving unit E by using the counter,and when the counted value reaches a value corresponding to the durationtime of the power saving mode, the storage 96 produces a control signalto stop delivery of the fast-forward pulses and supplies the controlsignal to the driving unit E. Accordingly, the time information storage96 also has a function of causing the resumed time indication to berestored to the current time. Incidentally, the contents of both thecounter and the memory are reset at the timing of the shift from theindication mode to the power saving mode.

Next, the driving control circuit 24 produces the driving pulsesdepending on the mode on the basis of the pulses outputted from thepulse synthesis circuit 22. First, in the power saving mode, the drivingcontrol circuit 24 stops the supply of the driving pulses. Then,immediately after the shift from the power saving mode to the indicationmode, the driving control circuit 24 supplies, as the driving pulses,fast-forward pulses with shorter pulse intervals causing the resumedtime indication to be restored to the current time. Then, afterfinishing the supply of the fast-forward pulses, the driving controlcircuit 24 supplies the driving pulses with normal pulse intervals tothe driving unit E.

[2.1.6] Power-Generation-State Detecting Portion

Next, the construction of the power-generation-state detecting portion91 will be described with reference to the drawing.

FIG. 6 is a circuit diagram of the power-generation-state detectingportion 91.

In FIG. 6, the first detecting circuit 97 produces a voltage detectingsignal Sv which assumes a high level when the magnitude of electromotivevoltage Vgen exceeds above a predetermined voltage, and a low level whenit falls below the predetermined voltage. On the other hand, the seconddetecting circuit 98 produces a power-generation-duration-time detectingsignal St which assumes a high level when the power generation durationtime exceeds above a predetermined time, and a low level when it fallsbelow the predetermined time. Also, the logical combination of thevoltage detecting signal Sv and the power-generation-duration timedetecting signal St is calculated by an OR circuit 975, and is thensupplied as a power-generation-state detecting signal S to the centralcontrol circuit 93. The power-generation-state detecting signal Sindicates the state of generating power when it assumes a high level,and the state of not generating power when it assumes a low level.Accordingly, as described above, if any one of the conditions determinedby the first and second detecting circuits 97 and 98 is satisfied, thepower-generation-state detecting portion 91 determines that power isgenerated. The first detecting circuit 97 and the second detectingcircuit 98 will be described below in detail.

[2.1.6.1] First Detecting Circuit

[2.1.6.1.1] Construction of First Detecting Circuit

In FIG. 6, the first detecting circuit 97 is mainly made up of acomparator 971, reference voltage sources 972, 973 for generating aconstant voltage, a switch SW1, and a retriggerable mono-multivibrator974. A value of the voltage generated by the reference voltage source972 is equal to the setting voltage value Va in the indication mode,whereas a value of the voltage generated by the reference voltage source973 is equal to the setting voltage value Vb in the power saving mode.The reference voltage sources 972, 973 are connected to a positive inputterminal of the comparator 971 through the switch SW1. The switch SW1 iscontrolled by the setting value changing portion 95 such that thereference voltage source 972 is connected to the positive input terminalof the comparator 971 in the indication mode, and the reference voltagesource 973 is connected to the positive input terminal of the comparator971 in the power saving mode. Also, the electromotive voltage Vgengenerated in the power generation unit A is supplied to a negative inputterminal of the comparator 971. Thus, the comparator 971 compares theelectromotive voltage Vgen with the setting voltage value Va or thesetting voltage value Vb, and produces a comparison result signal whichassumes a high level when the electromotive voltage Vgen is less (morenegative) than those setting voltage values (namely, has a largeramplitude), and which assumes a low level when the electromotive voltageVgen is more (less negative) than those setting voltage values (namely,has a smaller amplitude).

The retriggerable mono-multivibrator 974 produces a signal which istriggered so as to rise from a low level to a high level by a risingedge generating at the time when the comparison result signal rises froma low level to a high level, and which falls from a high level to a lowlevel after a predetermined time has elapsed. Also, when triggered againbefore the predetermined time elapses, the retriggerablemono-multivibrator 974 resets the counted time and starts over countingtime.

[2.1.6.1.2] Operation of First Detecting Circuit

Next, the operation of the first detecting circuit 97 will be describedwith reference to FIG. 7.

FIG. 7 is a timing chart for the first detecting circuit 97.

FIG. 7(a) shows the waveform of an electromotive voltage Vgen resultingafter half-wave rectification by the diode 47. In this embodiment, it isassumed that the setting voltage values Va and Vb are set to levelsshown in FIG. 7(a). Letting the current mode be the indication mode, theswitch SWI selects the reference voltage source 972 and supplies thesetting voltage value Va to the comparator 971.

Then, the comparator 971 compares the setting voltage values Va and theelectromotive voltage Vgen shown in FIG. 7(a), and produces thecomparison result signal shown in FIG. 7(b). In this case, theretriggerable mono-multivibrator 974 is triggered to rise from a lowlevel to a high level in synch with a rising edge of the comparisonresult signal which generates at the time t1 (see FIG. 7(c)).

Here, a delay time Td of the retriggerable mono-multivibrator 974 isshown in FIG. 7(b). In this case, because a period of time from one edgeel to a next edge e2 is shorter than the delay time Td, the voltagedetecting signal Sv maintains a high level.

On the other hand, letting the current mode be the power saving mode,the switch SW1 selects the reference voltage source 973 and supplies thesetting voltage value Vb to the comparator 971. In this embodiment,because the electromotive voltage Vgen does not exceed the settingvoltage value Vb, the retriggerable mono-multivibrator 974 is nottriggered. Accordingly, the voltage detecting signal Sv maintains a lowlevel.

Thus, the first detecting circuit 97 compares the electromotive voltageVgen with the setting voltage value Va or Vb, thereby producing thevoltage detecting signal Sv.

[2.1.6.2] Second Detecting Circuit

[2.1.6.2.1] Construction of Second Detecting Circuit

In FIG. 6, the second detecting circuit 98 is made up of an integratingcircuit 981, a gate 982, a counter 983, a digital comparator 984, and aswitch SW2.

First, the integrating circuit 981 is made up of a MOS transistor 2, acapacitor 3, a pull-up resistor 4, and an inverter circuit 5. Theelectromotive voltage Vgen is connected to a gate of the MOS transistor2, whereby the MOS transistor 2 repeats on- and off-operations inaccordance with the electromotive voltage Vgen to control charging ofthe capacitor 3. If a switching means is constructed of a MOStransistor, the integrating circuit 981 including the inverter circuit 5can be constructed of an inexpensive CMOS IC. However, the switchingelement and voltage detecting means may be constructed of bipolartransistors. The pull-up resistor 4 serves to fix a voltage value V3 ofthe capacitor 3 to the potential Vss in the state of not generatingpower, and also to generate a leakage current the state of notgenerating power. The pull-up resistor 4 has a high resistance value onthe order of several tens to several hundreds MΩ, and may be constructedof a MOS transistor having a large resistance at turning-on. Theinverter circuit 5 connected to the capacitor 3 determines the voltagevalue V3 of the capacitor 3. The inverter circuit 5 outputs a detectionsignal Vout. Here, a threshold of the inverter circuit 5 is set to asetting voltage value Vbas that is fairly smaller than the settingvoltage value Vo used in the first detecting circuit 97.

The reference signal supplied from the pulse synthesis circuit 22 andthe detection signal Vout are supplied to the gate 982. Accordingly, thecounter 983 counts the reference signal during a period in which thedetection signal Vout maintains a high level. A counted value issupplied to one input of the digital comparator 984. Also, the settingtime value To corresponding to the setting time is supplied to the otherinput of the digital comparator 984. When the current mode is theindication mode, the setting time value Ta is supplied through theswitch SW2, and when the current mode is the power saving mode, thesetting time value Th is supplied through the switch SW2. Additionally,the switch SW2 is controlled by the setting value changing portion 95.

The digital comparator 984 outputs the comparison result signal, as apower-generation-duration-time detecting signal St, in synch with afalling edge of the detection signal Vout. Thepower-generation-duration-time detecting signal St assumes a high levelwhen the duration time exceeds above the setting time, and a low levelwhen the duration time falls below the setting time.

[2.1.6.2.2] Operation of Second Detecting Circuit

Next, the operation of the second detecting circuit 98 will be describedwith reference to FIG. 8.

FIG. 8 is a timing chart for explaining the operation of the seconddetecting circuit 98.

When generation of AC power shown in FIG. 8(a) is started in the powergeneration unit A, the power generator 40 produces an electromotivevoltage Vgen shown in FIG. 8(b) through the diode 47. When a voltagevalue of the electromotive voltage Vgen falls from Vdd′ down to Vssafter the start of power generation, the MOS transistor 2 is turned onto start charging of the capacitor 3. The potential at V3 is fixed tothe Vss side by the pull-up resistor 4 in the state of not generatingpower, but begins to rise toward the Vdd side when the charging of thecapacitor 3 starts subsequent to the power generation. Then, when thevalue of the electromotive voltage Vgen increases toward Vss and the MOStransistor 2 is turned off, the charging of the capacitor 3 is stopped,but the potential at V3 is held at the same level as shown in FIG. 8(c).The above operation is repeated during a period in which the powergeneration is continued, and the potential at V3 is stabilized afterrising to Vdd. When the potential at V3 rises above the threshold of theinverter circuit 5, the detection signal Vout as an output of theinverter circuit 5′ shifts from a low level to a high level, whereuponthe power generation is detected. A response time to the detection ofpower generation can be optionally set by connecting a current limitingresistor, or changing a capability of the MOS transistor to adjust thevalue of a charging current to the capacitor 3, or changing the capacityvalue of the capacitor 3.

When the power generation is stopped, the electromotive voltage Vgen isstabilized at the Vdd level and therefore the MOS transistor 2 is keptin an off-state. The voltage at V3 is continuously held for a while bythe capacitor 3, but the charge in the capacitor 3 escapes due to aslight leakage current through the pull-up resistor 4. Accordingly, V3starts to gradually fall from Vdd toward Vss. Then, when V3 falls belowthe threshold of the inverter circuit 5, the detection signal Vout as anoutput of the inverter circuit 5′ shifts from a high level to a lowlevel, whereupon it is detected that power is not generated (see FIG.8(d)). A response time to the detection of non-power generation can beoptionally set by changing the resistance value of the pull-up resistor4 to adjust a leakage current from the capacitor 3.

Gating the reference signal by the detection signal Vout produces asignal shown in FIG. 8(e), and the produced signal is counted by thecounter 983. A counted value is compared in the digital comparator 984with the value corresponding to the setting time at timing T1. Here, ifa high level period Tx of the detection signal Vout is longer than thesetting time value To, the power-generation-duration-time detectingsignal St changes from a low level to a high level at the timing T1 asshown in FIG. 8(f).

The electromotive voltage Vgen produced depending on a difference inrotational speed of the power generating rotor 43 and the detectionsignal Vout resulting from the electromotive voltage Vgen will now bedescribed with reference to FIG. 9.

FIG. 9 is a conceptual view for explaining the electromotive voltageVgen produced depending on a difference in rotational speed of the powergenerating rotor 43 and the relation of the detection signal Vout withrespect to the electromotive voltage Vgen.

In particular, FIG. 9(a) represents the case where the rotational speedof the power generating rotor 43 is small, and FIG. 9(b) represents thecase where the rotational speed of the power generating rotor 43 islarge. A voltage level and cycle (frequency) of the electromotivevoltage Vgen change depending on the rotational speed of the powergenerating rotor 43. In other words, the higher the rotational speed,the larger is the amplitude of the electromotive voltage Vgen and theshorter is the cycle thereof. Therefore, the length of an output holdingtime (power generation duration time) of the detection signal Voutchanges depending on the rotational speed of the power generating rotor43, i.e., the intensity of power generation. Specifically, when themotion is small as shown in FIG. 9(a), the output holding time is ta,and when the motion is large shown in FIG. 9(b), the output holding timeis tb. The relationship between ta and tb is ta<tb. The intensity ofpower generation in the power generator 40 can be determined from thelength of the output holding time of the detection signal Vout.

[2.2] Operation of Timepiece

Next, mode setting steps for carrying out a mode changing process in thetimepiece 1 of this second embodiment will be described.

FIG. 10 is a flowchart showing a summary of the mode setting steps.

First, the current mode is determined in step 71. If the current mode isunder power saving, counting of the suspension time is continued by thetime information storage 96 in step 74. Then, the setting values Vo andTo in the power-generation-state detacting portion 91 are set to thevalues Vb and Tb for the power saving mode in step 75. On the otherhand, if the current mode is the indication mode, the driving controlportion 24 controls the driving circuit 30 to produce the driving pulsesand effects the time indication in step 72. Then, the setting values Voand To in the power-generation-state detecting portion 91 are set to thevalues Va and Ta for the indication mode in step 73.

Next, a power generation level (electromotive voltage) is detected instep 76. If it is determined in step 76 that the electromotive voltageis produced even though its level is small, the power generationduration time Tgen is counted up in step 77. Then, the power generationduration time Tgen is compared with the setting time To in step 78. Ifthe power generation duration time Tgen is not less than the settingtime To, processing goes to step 80 upon a decision that powergeneration is detected. If it is determined in step 78 that the powergeneration duration time Tgen does not reach the setting time To, theelectromotive voltage Vgen is compared with the setting value Vo in step79. If the electromotive voltage Vgen reaches the setting value Vo,processing goes to step 80 upon a decision that power generation isdetected. In step 80, the mode is determined again. If the mode is notthe power saving mode, the non-power-generation time Tn is cleared instep 81, following which processing returns to step 71 and continues thetime indication in step 72. Conversely, if the mode is the power savingmode, the charged voltage VC of the power supply unit B is determined instep 82. If the power supply unit B is sufficiently charged, the mode isshifted from the power saving mode to the indication mode and the powersaving mode is cleared in step 83. When the time is indicated again uponthe shift to the indication mode, the time indication is fast forwardedin accordance with the suspension time counted by the time informationstorage 96, and normal rotation of the hands per second is started afterrestoring to the current time, as described above. As a result, the usercan view the precise time indicated after returning to the indicationmode.

On the other hand, if the electromotive voltage is not detected in step76, or if the power generation duration time Tgen does not reach thesetting time To and the electromotive voltage Vgen also does not reachthe setting value Vo, processing goes to step 85 upon a decision thatpower generation is not detected, where the mode at that time isdetermined. In this respect, when the electromotive voltage is notdetected in step 76, the power generation duration time Tgen is clearedin step 84. If the mode is determined to be the power saving mode instep 85, processing returns to step 71 directly to continue counting-upof the suspension time. If the mode is determined to be the indicationmode, the non-power-generation time Tn is counted up in step 86, andwhether a predetermined non-power-generation time is continued or not isdetermined in step 87. If the non-power-generation time Tn has elapsed,the mode is shifted from the indication mode to the power saving mode instep 88, thereby starting the power saving. In step 88, the operationsof both the driving control circuit 24 and the driving circuit 30 arestopped to reduce power consumption of the motor 10, and counting of thesuspension time is started by the time information storage 96.

[2.3] Advantages of Second Embodiment

Thus, in the timepiece 1 of this embodiment, the time indication isstopped or resumed depending on whether power is generated or not. Asdescribed above, the power generator 40 in this embodiment is such asystem that power is generated by motion of the user's arm or vibrationwith the aid of the rotating weight 45. Accordingly, the fact that powergeneration is detected means that the timepiece is fitted on the user'sarm, or that the user carries the timepiece while putting it in a pocketor the like. In view of the above, when power generation is detected,the mode is shifted to the indication mode in which the time isindicated, upon a decision that the timepiece is carried by the user.Conversely, when power generation is not detected, the mode is shiftedto the power saving mode in which the time is not indicated, upon adecision that the timepiece is not carried by the user. As a result, theenergy accumulated in the large-capacity capacitor 48 can be saved.

Further, in the timepiece 1 of the second embodiment, it is determinedthat power generation is detected when the predetermined electromotivevoltage Vgen is detected, and when power generation is continued for thepredetermined time.

Therefore, even when the mode is shifted to the power saving mode in acondition of the timepiece being not carried by the user and powergeneration is then accidentally induced for some reason, e.g.,vibration, the mode is kept from shifting to the indication mode if theelectromotive voltage is weak and the duration time is short. Uselessconsumption of energy can be thus prevented. On the other hand, in theindication mode, since the setting value Vo is set to be lower than inthe power saving mode, it is determined that power generation isdetected, if the electromotive voltage is obtained even though thedetected electromotive voltage Vgen is somewhat low. As a result, thetime indication is continued so long as power is generated even at a lowlevel. Also, in the indication mode, since the setting time To for thepower generation duration time Tgen is also set to be shorter, the timeindication is maintained so long as power is generated even for a shorttime.

Moreover, in the timepiece 1 of the second embodiment, thenon-power-generation time Tn is measured, and the mode is not shifted tothe power saving mode unless the non-power-generation time reaches thesetting time.

Accordingly, it is possible to maintain the time indication not only inthe case where motion of the user is stopped and power is not generatedfor a short time, but also in the case where the user takes off thewristwatch for a period of time such as during a meeting. Also, the timemay be continuously indicated even when the user takes off thewristwatch all night. As an alternative, for the purpose of savingenergy, the mode may be shifted to the power saving mode if the usertakes off the wristwatch for a period of about five minutes.

As described above, with the timepiece 1 of this second embodiment,whether the timepiece is carried by the user or not can be automaticallydetermined based on the power generation state. Then, the timepiece cansufficiently function as a wristwatch or the like by indicating the timewhen carried by the user, and can reduce consumption of energy withoutindicating the time when not carried by the user. Accordingly, the poweronce charged in the large-capacity capacitor 48 can be effectivelyutilized. Even with the timepiece left standing for a long time, thetime is not indicated and only the elapsed time is measured during sucha period of time. When the user wears the timepiece again, the timeindication is resumed and restored to the current time, therebyindicating the precise time. With no need of employing a capacitor beingso large in capacity, therefore, a small size wristwatch or the likecapable of keeping time for a long time with good accuracy can berealized by incorporating, in place of a battery, a power generator anda capacitor having an appropriate capacity. Also, since the capacity ofa capacitor is not required to be so large, a timepiece can be realizedwhich has a good start-up characteristic, and can resume the indicationand restore to the current time as soon as power generation is started.In addition, with the timepiece of this embodiment, the user can alwayssee the time regardless of surrounding conditions even in a dark place,for example, when carried by the user, and therefore the user is freefrom inconvenience.

[2.4] Modifications of Second Embodiment

[2.4.1] First Modification

In the above description of the second embodiment, thepower-generation-state detecting portion 91 detects the power generationstate based on the electromotive voltage Vgen from the power generationunit A. However, the power generation state may be detected in the powersupply unit B based on a charging current flowing into thelarge-capacity capacitor 48.

In this case, as shown in FIG. 11, a current-to-voltage converter 100may be disposed upstream of the first detecting circuit 97 and thesecond detecting circuit 98. The current-to-voltage converter 100 ismade up of a current detecting resistor R and an operational amplifierOP for detecting a potential difference across the resistor R.

[2.4.2] Second Modification

Further, the above description of the second embodiment has been madeemploying the power generation state detecting portion 91 which includesboth the first detecting circuit 97 for comparing the electromotivevoltage Vgen with the setting value Vo and then determining whetherpower generation is detected, and the second detecting circuit 98 forcomparing the power generation duration time Tgen, during which theelectromotive voltage Vgen not lower than the voltage Vbas fairlysmaller than the setting value Vo is obtained, with the setting value Toand then determining whether power generation is detected. However,whether power is generated or not can be of course also determined byusing one of the first and second detecting circuits 97 and 98.

[3] Third Embodiment

Next, a timepiece according to a third embodiment of the presentinvention will be described.

The timepiece of the third embodiment is similarly constructed as thetimepiece of the second embodiment except the construction of the powergeneration state detecting portion 91.

The frequency of power generated in the power generation unit A changesdepending on the intensity of power generation. For example, when thetimepiece 1 put on a desk is slightly moved by some accident, thefrequency of the generated power is low, but when the user is walkingwhile wearing the timepiece 1 on his wrist, the frequency of thegenerated power is increased. Also, when the user tries to charge thetimepiece 1 by shaking his wrist, the frequency of the generated poweris further increased. This embodiment has been made in view of the abovepoint, and intends to detect the power generation state based on thefrequency of the generated power.

[3.1] Construction of Power-Generation-State Detecting Portion

FIG. 12 shows a block diagram of a power-generation-state detectingportion 91′ according to the third embodiment.

Also, FIG. 13 shows a timing chart of the power-generation-statedetecting portion 91′ according to the third embodiment.

The power-generation-state detecting portion 91′ is made up of acomparator 971, a reference voltage source 972 for generating a constantvoltage, a switch SW2, and a timer 975, as well as an SR flip-flop 976,a gate 977, a counter 978, and a digital comparator 979.

The reference voltage source 972 generates the setting voltage value Vain the indication mode, and is connected to a positive input terminal ofthe comparator 971. Also, the electromotive voltage Vgen generated inthe power generation unit A, shown in FIG. 13(a), is supplied to anegative input terminal of the comparator 971. Thus, the comparator 971compares the electromotive voltage Vgen with the setting voltage valueVa, and produces a comparison result signal which assumes a high levelwhen the electromotive voltage Vgen is less (greater negative amplitude)than the setting voltage value Va, and which assumes a low level whenthe electromotive voltage Vgen is more (less negative amplitude) thanthe setting voltage values Va (see FIG. 13(b)).

The comparison result signal is supplied to a set terminal of the SRflip-flop 976, and an output signal of the timer 975 is supplied to areset terminal of the SR flip-flop 976. The timer 975 is designed so asto start counting of time in synch with rising of an output signal ofthe SR flip-flop 976, and to fall after upon the elapse of apredetermined time. Assuming here the timer counting time to be Ts, asshown in FIG. 13(c), the output signal of the SR flip-flop 976 changesfrom a low level to a high level in synch with each rising edge e3, e4of the comparison result signal, and falls from a high level to a lowlevel after maintaining a high level for the time Ts.

The gate 977 outputs the logical and of the output signal of the SRflip-flop 976 and the comparison result signal. The counter 978 countsan output signal of the gate 977, and then outputs a counted value Z tothe digital comparator 979. A setting value X1, X2 is selectivelysupplied to the digital comparator 979 through the switch SW2. Theswitch SW2 is controlled by the setting value changing portion 95, andsupplies, to the digital comparator 979, the setting value X1 in theindication mode and the setting value X2 in the power saving mode. Thesetting value X1 corresponds to a frequency f1 of the generated powerbased on which it is possible to determine whether power is generated ina normal carried state, and the setting value X2 corresponds to afrequency f2 of the generated power based on which it is possible todetermine whether forcible charging is made. The digital comparator 979is designed so as to compare the setting value X1 or X2 with the countedvalue Z of the counter 978 at a falling edge of the signal from the gate977.

When the current operating mode is the power saving mode, apower-generation-state detecting signal S indicating the state of powergeneration is produced when the frequency of power generated in thepower generation unit A exceeds above f2. Accordingly, the power savingmode is not cleared when the timepiece is in a normal carried state, andthe mode is shifted from the power saving mode to the indication modeonly when the user tries forcible charging (by shaking his wrist) withthe intention of clearing the power saving mode. Thus, even when thetimepiece 1 is slightly touched or the like, the power saving mode isnot cleared and useless consumption of power is avoided.

On the other hand, when the current operating mode is the indicationmode in which the time is indicated, a power-generation-state detectingsignal S indicating the state of power generation is produced when thefrequency of power generated in the power generation unit A falls belowf1. Since the frequency of the generated power f1 is set, as describedabove, to a value based on which it is possible to determine whetherpower is generated in a normal carried state, the mode can be promptlyshifted from the indication mode to the power saving mode by preciselydetecting a condition where the timepiece is not used. As a result,useless consumption of power is avoided.

[4] Fourth Embodiment

Each of the above-described embodiments employs, as the power generator40, an electromagnetic induction power generator wherein rotating motion(=kinetic energy) of the rotating weight 45, produced when the timepieceis carried by the user, is transmitted to the rotor 43, and theelectromotive voltage Vgen is generated in the output coil 44 with therotation of the rotor 43. In this fourth embodiment, the power generator40 is replaced by a power generator of the type that it is brought intoa power-generation disabled state depending on ambient environment evenwhen the timepiece is carried with the user.

In the case of using such a power generator, when the operating mode iscontrolled depending on the power generation state of the powergenerator, the timepiece is not always brought into the state ofgenerating power even with the timepiece being carried by the user, andis not always brought into the state of not generating power even withthe timepiece being not carried by the user.

In the above case, the problem is that even when the timepiece is in thestate carried by the user and the power generator still remains in thestate of not generating power, the operating mode may be shifted fromthe power saving mode to the indication mode (normal operating mode). Ifsuch an event happens, the timepiece would turn into the indication modein spite of being in the state of not generating power, and the powerwould be so diminished as to stop the timepiece.

The power generator that possibly causes the above problem is, e.g., asolar cell. In the solar cell, power is generated by converting opticalenergy (corresponding to first energy) of extraneous light, such assunlight, into electric energy with photoelectric conversion.

The fourth embodiment will be described below in detail in connectionwith an example in which a solar cell is employed as the powergenerator.

FIG. 14 is a block diagram showing a schematic construction of atimepiece of the fourth embodiment. In FIG. 14, the same components asthose in the first embodiment of FIG. 2 are denoted by the samenumerals, and detailed description thereof is omitted here.

The fourth embodiment differs from the first embodiment in that acarried-state detecting unit 400 for determining whether the timepieceis in the state carried by the user, i.e., whether the user is wearingthe timepiece, is provided, and a central control circuit 93A restoresthe operating mode from the power saving mode to the indication modeonly when the timepiece 1A is in the state carried by the user and apower generator (solar cell) 40A is in the state of generating power.

[4.1] Carried-state Detecting Unit

Concrete examples of the carried-state detecting unit will be firstdescribed.

Conceivable constructions of the carried-state detecting unit are, forexample, below.

(1) A carried-state detecting unit including an acceleration sensor todetect acceleration when the timepiece is carried by the user.

(2) A carried-state detecting unit including a contact electrode sensorto detect a change in current value, voltage value, resistance value, orcapacitance value between electrodes when the user is wearing thetimepiece.

(3) A carried-state detecting unit including a mechanical contact sensorto detect whether the user is wearing the timepiece or not, by detectingan on- or offstate of a mechanical contact when the user is wearing thetimepiece.

[4.1.1] Carried-state Detecting Unit Including Acceleration Sensor

In a carried-state detecting unit including an acceleration sensor, theacceleration sensor is disposed, by way of example, to detectacceleration in the planar direction of a timepiece dial. Theacceleration sensor detects acceleration corresponding to motion of thetimepiece when the user is wearing the timepiece, and the carried-statedetecting unit detects that the user is wearing the timepiece, i.e.,that the timepiece is carried by the user, when acceleration not smallerthan a predetermined acceleration set beforehand is detected.

In this case, various states in which the timepiece is carried by theuser can be detected by setting the predetermined acceleration to avalue corresponding to desired acceleration to be detected.

Further, by detecting the carried state of the timepiece only whenacceleration not smaller than the predetermined acceleration iscontinuously detected for a period of time not less than a predeterminedtime set beforehand, the operating mode is surely avoided fromerroneously shifting from the power saving mode to the indication mode(normal operating mode).

[4.1.2] Carried-state Detecting Unit Including Contact Electrode Sensor

This carried-state detecting unit is constructed, by way of example,such that a pair of contact electrodes are provided on the backside ofthe timepiece 1A so as to contact the user's arm when the user puts thetimepiece on the arm.

In this case, a resistance value or a capacitance value between thecontact electrodes resulting when the user is not wearing the timepiece,is set to a proper value beforehand. The carried state of the timepieceis detected by detecting a change in detected resistance value, detectedcurrent value, detected voltage value, or detected capacitance valuebetween electrodes, which occurs when the user wears the timepiece 1A.

Also, in that case, by detecting the carried state of the timepiece onlywhen a change in detected resistance value, detected current value,detected voltage value, or detected capacitance value is continuouslydetected for a period of time not less than a predetermined time setbeforehand, the operating mode is surely avoided from erroneouslyshifting from the power saving mode to the indication mode (normaloperating mode).

[4.1.3] Carried-state Detecting Unit Including Mechanical Contact Sensor

This carried-state detecting unit is constructed, by way of example,such that a mechanical contact switch is provided on a fastener of aband (watch band) for holding the timepiece 1A on the arm, and the unitdetects turning of the mechanical contact switch to an on- or off-stateoccurring when the user fits the band around the arm.

Alternatively, a movable mechanical contact switch is provided in themechanism, and the carried state of the timepiece is detected uponturning-on of the mechanical contact switch when the timepiece 1A isinclined to a predetermined angle set beforehand (e.g., when a dial ofthe timepiece takes a posture vertical to the ground surface).

Further, the carried-state detecting unit of this type may beconstructed such that the number of times of turning-on/off is countedduring a predetermined period of time, the counted number is comparedwith a reference number set beforehand, and the carried state of thetimepiece is detected when the mechanical contact switch turns on andoff in excess of the reference number.

In place of any of the above carried-state detecting units or inaddition to it, a power generator for generating power based on kineticenergy such as energy of rotation of a rotating weight, a powergenerator for generating power based on pressure energy by using apiezoelectric device or the like, or a power generator for generatingpower based on thermal energy by using a thermoelectric device such as athermocouple may be used as a power generator. In this case, the carriedstate of the timepiece can be detected depending on the power generationstate of the power generator.

[4.2] Operation of Principal Part of Fourth Embodiment

The operation of a principal part of the fourth embodiment will bedescribed below. Suppose here that the operating mode is the indicationmode (normal operating mode) in an initial state.

The non-power-generation time measuring circuit 99 of the centralcontrol circuit 93A measures the non-power-generation time Tn duringwhich power generation in a solar cell, used as the power generator 40A,is not detected by the first detecting circuit 97 and the seconddetecting circuit 98.

Then, regardless of whether the carried-state detecting unit 400produces a detection output, i.e., in any of the cases where thetimepiece is in the carried state and in the not-carried state, thecentral control circuit 93A shifts the operating mode from theindication mode to the power saving mode when the non-power generationtime Tn exceeds a predetermined setting time.

The thus-set operating mode is stored in the mode storage 94, and thestored information is supplied to the driving control circuit 24, thetime information storage 96, and the setting value changing portion 95.Upon the shift from the indication mode to the power saving mode, thedriving control circuit 24 stops supply of the pulse signal to thedriving circuit 30, thereby stopping the operation of the drivingcircuit 30. Accordingly, the motor 10 ceases rotation and the timeindication is stopped.

Also, upon the shift from the indication mode to the power saving mode,the time information storage 96 starts operation as a suspension timecounter which receives the reference signal produced by the pulsesynthesis circuit 22 and stores a duration time of the power savingmode.

Under the power saving mode, the central control circuit 93A monitorsthe detection output of the carried-state detecting unit 400 and thepower-generation detection outputs of the first detecting circuit 97 andthe second detecting circuit 98, and returns the operating mode from thepower saving mode to the indication mode only when the timepiece 1A isin the state carried by the user and the solar cell 40A serving as thepower generator is in the state of generating power.

Then, upon the shift from the power saving mode to the indication mode,the central control circuit 93A counts fast-forward pulses supplied fromthe driving control circuit 24 to the driving circuit 30 and causes theresumed time indication to be restored to the current time.

[4.3] Advantages of Fourth Embodiment

With the fourth embodiment, as described above, when the timepiece isnot in the carried state (when the user is not employing the timepiece),the operating mode is kept from shifting from the power saving mode tothe indication mode (normal operating mode), and useless consumption ofpower can be avoided.

Also, when the operating mode is shifted from the power saving mode tothe indication mode, the user can see the precise time indicationwhenever the user wants to know the time because the timepiece is in thecarried state and in the used state, i.e., because the timepiece is in acondition where the power generator generates power in an amount enoughfor the indication.

[4.4] Modifications of Fourth Embodiment

[4.4.1] First Modification

In the above description, the central control circuit 93A shifts theoperating mode from the indication mode to the power saving mode whenthe non-power generation time Tn exceeds the predetermined setting time,in any of the cases where the timepiece 1A is in the carried state andin the not-carried state. However, the operating mode may be shifted tothe power saving mode only when the voltage of the large-capacitycapacitor 48 serving as the power supply corresponds to a voltagecapable of restoring the current time when the mode will be shifted tothe indication mode again subsequent to the shift to the power savingmode, or only when the voltage of the large-capacity capacitor 48corresponds to a voltage capable of performing at least the normal handrotation when the mode win be shifted to the indication mode againsubsequent to the shift to the power saving mode.

[4.4.2] Second Modification

The above description has been made in connection with the case wherethe solar cell serving as the power generator 40A does not produce thegenerated power (i.e., it is brought into the state of not generatingpower). However, the present invention is also applicable to the casewhere power generation is insufficient and the generated power is lowerthan a predetermined voltage.

[4.4.3] Third Modification

The above description has been made in connection with the case ofemploying the solar cell as the power generator. However, similaradvantages as obtainable with the fourth embodiment can also be obtainedin the case of employing a manually wound piezoelectric power generatorincluding a manually winding device to apply vibration to apiezoelectric device, a spring power generator for generating power byutilizing energy accumulated in a spring, or an electromagnetic wavepower generator for generating power by utilizing electromagnetic energypropagating in a space.

[4.4.3.1] First Concrete Form of Third Modification of Fourth Embodiment

A manually winding device is provided and rotated to apply vibration toa piezoelectric member.

[4.4.3.2] Second Concrete Form of Third Modification of FourthEmbodiment

In place of the power generator 40A, a power generator receiving strayelectromagnetic waves can be employed which generates power withelectromagnetic induction by utilizing electromagnetic wave energy ofelectric waves for broadcasting and communications. More specifically, aplurality of tuning circuits are provided so as to be able to tune andresonate with those of electric waves propagating in a space which haveparticular frequencies different from each other, and to take out theelectric waves of the particular frequencies in the form of power.

[4.4.3.3] Third Concrete Form of Third Modification of Fourth Embodiment

In place of the power generator 40A, a thermal power generator having athermoelectric transducer, such as a thermocouple, and generating powerby utilizing thermal energy is employed. This form can also providesimilar advantages as obtainable with the fourth embodiment.

[5] Modifications of Embodiments

[5.1] First Modification

While the above embodiments have been each described in connection with,by way of example, the timepiece indicating the time with the steppingmotor 10, the present invention is of course also applicable to anothertype of timepiece indicating the time with an LCD, etc.

In this case, the time can be continuously counted for a long time whilesaving power consumed by the LCD, and the precise current time can bealways displayed as required.

[5.2] Second Modification

Also, while the above embodiments have been each described in connectionwith, by way of example, the timepiece indicating the hour, minute andsecond by one motor, the time may be indicated by driving the hour hand,the minute hand, and the second hand by using a plurality of motors.

As a result, the motors can be driven independently of each other torotate the hands in a stepwise manner, and the amount of rotation of thehands necessary for restoring to the current time upon the shift fromthe power saving mode to the indication mode (normal operating mode) canbe reduced in comparison with the case of driving all the hands by onemotor. It is hence possible to reduce power consumption required forrestoring the hands to the current time with fast forward rotationrather than power consumption required for rotating the hands in theindication mode.

Further, by combining backward hand rotation (hand rotation in thecounterclockwise direction) and forward hand rotation with each other,the maximum amount of rotation of the hands can be reduced to an amountcorresponding to a ½ period (e.g., 6 hours when the hour hand indicates12 hours), and power consumption required for restoring to the currenttime can be further reduced.

As a concrete example of driving the hands by a plurality of motors, thetimepiece can be constructed such that the hour and minute hands aredriven by a first motor and the second hand is driven by a second motor.In this case, the timing to stop the time indication can also be changedfor each motor.

More specifically, the power saving mode is prepared in two stages. Whenthe operating mode is shifted from the indication mode to a first powersaving mode, driving of only the second motor is stopped to cease thesecond hand only. This is because the user can still easily grasp thetime even with only the second hand ceased, and power consumption can beefficiently reduced by ceasing the second motor which drives the secondhand and consumes a large amount of energy.

Then, upon the shift from the first power saving mode to the secondpower saving mode, the first motor for driving the hour and minute handsis also stopped and power consumption can be further reduced.

As a result, the second indication consuming a large amount of energybecause of short intervals of hand rotation can be stopped at earliertiming at which the non-power-generation time is short, whereas the hourand minute indication consuming a relatively small amount of energybecause of relatively long intervals of hand rotation can be continuedas long as possible.

Moreover, the timepiece may be constructed so as to drive the hour handby a first motor, the minute hand by a second motor, and the second handby a third motor.

By thus driving the hands by a plurality of motors, a time required forrestoring to the current time can be further shortened.

In addition, the timepiece may be constructed such that the user canchange the timing to stop the time indication for each motor inaccordance with the user's preference.

Likewise, in a timepiece having a calendar function, a motor for drivinga calendar mechanism can be provided separately.

[5.3] Third Modification

While each of the above-described embodiments employs, as the powergenerator 40, an electromagnetic induction power generator whereinrotating motion (=kinetic energy) of the rotating weight 45 istransmitted to the rotor 43 and the electromotive voltage Vgen isgenerated in the output coil 44 with the rotation of the rotor 43, thepresent invention is not limited to those embodiments.

[5.3.1] First Form of Third Modification

A power generator producing rotary motion by restoring forces (=kineticenergy) of a spring and generating an electromotive voltage with therotary motion can be employed in place of the power generator 40.

[5.3.2] Second Form of Third Modification

A power generator utilizing the piezoelectric effect to convert pressureinto electric energy and generating electric power by applying externalor self-excited vibration or displacement to a piezoelectric member(piezoelectric device) can be employed in place of the power generator40.

More specifically, a vibrating piece including a piezoelectric layer isvibrated with the rotation of the rotating weight, thereby generatingpower.

As an alternative, a manually winding device may be provided so thatvibration is applied to a piezoelectric member by rotating the manuallywinding device.

[5.3.3] Third Form of Third Modification

A power generator utilizing the thermoelectric effect to convert thermalenergy into electric energy and generating electric power by applying atemperature difference to a thermoelectric transducer, such as athermocouple, can be employed in place of the power generator 40.

More specifically, a heat radiating plate is provided on the dial sideof the timepiece, a heat absorbing plate for absorbing heat from theuser's body is provided on the back side of the timepiece, and the heatradiating plate and the heat absorbing plate are connected to each otherby a heat conducting member formed of a material having high thermalconductivity. With this arrangement, a temperature difference can beefficiently held, and efficient power generation can be achieved.

[5.3.4] Fourth Form of Third Modification

The timepiece can be constructed so as to include a plurality of powergenerators (corresponding to auxiliary power generators) by providingplural ones of the power generators according to the first to thirdforms of the above third modification in place of the power generator40, or by providing any of the power generators according to the firstto fifth forms of the above third modification in addition to the powergenerator 40.

With the above arrangement, power generation can be continued by any ofthe power generators, and more stable power generation and hence stablesupply of source power can be achieved.

[5.4] Fourth Modification

While the above embodiments have been each described in connection with,by way of example, the timepiece 1 of wristwatch type, the presentinvention is not limited to such a timepiece. Electronic equipment, inwhich the above-described power generation unit A, power supply unit Band control unit C can be provided, may be a pocket watch or the like inaddition to a wristwatch.

The present invention is also adaptable for other electronic equipmentsuch as pocket-size calculators, portable phones, portable personalcomputers, electronic pocketbooks, portable radios, portable VTRs, andportable navigation devices.

In this case, a power consuming portion operating with power suppliedfrom the power supply unit B is provided, the power generation state ofthe power generation unit A is detected by the power-generation-statedetecting portion 91, and the control unit C selectively controls themode in accordance with a detection result between a power saving modein which the operation of the power consuming portion is stopped and anoperative mode in which the power consuming portion is operated.Specifically, the operative mode corresponds to a used state of a pocketcalculator, a portable phone, etc., and the power saving modecorresponds to a non-used state thereof. In the power saving mode,however, the power-generation-state detecting portion 91 is suppliedwith power to be able to determine whether the user is wearing theelectronic equipment. In electronic equipment having display units,particularly, it is desired that screen display be not effected in thepower saving mode, but effected in the normal operating mode. Thisenables the user to know whether the mode is in the power saving mode orthe normal operating mode, by seeing the display unit.

Further, in that case, the operating condition at the time of shift tothe power saving mode is stored in a memory or the like, and theoperating condition with the elapse of time during the power saving modeis also continuously accumulated. Upon restoring to the normal operatingmode, the stored and accumulated information is utilized to restore theoperating condition based on the current information given by theinformation including the progress condition, or to restore the normaloperating condition based on the current information added with theinformation including the progress condition.

A self-contained navigation device, for example, can be constructed suchthat the condition of traveling in the course is not displayed butaccumulated, and the normal operating condition is then restored todisplay the current position based on an accumulated result, or theinformation regarding the condition of traveling in the course is thendisplayed when the normal operating mode is restored.

[5.5] Fifth Modification

In each of the above-described embodiments, the user is required toshake the wrist to forcibly charge the timepiece 1 when the mode isshifted from the power saving mode to the indication mode.

On that occasion, power is generated in a larger amount than when theuser wearing the timepiece 1 is in normal daily activities, and a levelof electromagnetic noise occurring in the power generator 40 may becomelarger than when the timepiece 1 is usually carried with the user.

As a result, it is thought that the stepping motor 10 is affected by theelectromagnetic noise and the indicated ion time becomes incorrect.

In view of the above, this fifth modification is constructed so as todetect the state where power is forcibly generated by the user shakingthe wrist, and to produce driving pulses having a wider width in thedriving unit E upon detection of such a state. This arrangement enablesthe stepping motor 10 to be surely operated with the driving pulseshaving a wider width even when the level of electromagnetic noiseoccurring in the power generator 40 is increased.

Also, when the timepiece 1 is forcibly charged by the user shaking hiswrist, there is a risk that a large charging current may increasevariations of the supply source voltage due to the internal resistanceof the large-capacity capacitor 48 and may adversely affect the circuitoperation.

In view of the above, the timepiece may be constructed so as to detectthe state where power is forcibly generated by the user shaking hiswrist, and to short-circuit across the power generating stator 42 upondetection of such a state. With this arrangement, variations of thesupply source voltage can be suppressed and the circuit can be reliablyoperated.

[5.6] Sixth Modification

The first detecting circuit 97 and the second detecting circuit 98described in the above first and second embodiments and thepower-generation-state detecting portion 91′ described in the abovethird embodiment can be combined with each other appropriately togenerate power.

In other words, the state of generating power may be detected by any ofcombinations of the electromotive voltage Vgen and the power generationduration time, the power generation duration time and the frequency ofthe generated power, the frequency of the generated power and theelectromotive voltage Vgen, and the electromotive voltage Vgen, thepower generation duration time and the frequency of the generated power.

Further, the parameter to be detected may be the electromotive voltage,or the charging current described in the modification of the secondembodiment.

Stated otherwise, the state of generating power can be detected by usingany one of detection based on a voltage, detection based on a current,detection based on a power generation duration time, and detection basedon frequency of the generated power.

[5.7] Seventh Modification

In the first detecting circuit 97 and the second detecting circuit 98described in the above first and second embodiments and thepower-generation-state detecting portion 91′ described in the abovethird embodiment, the setting value as a comparison reference is changeddepending on the current mode. However, the detected result may becompared with a plurality of setting values to detect the state of notgenerating power (the state not carried by the user), the state carriedby the user, and the state of forcibly generating power.

[5.8] Eighth Modification

While the reference potential (GND) is set to Vdd (higher potentialside) in each of the above-described embodiments, it is a matter ofchoice that the reference potential (GND) may be set to Vss (lowerpotential side).

In this case, the setting voltage value Vo and Vbas each represent apotential difference relative to a detection level set on the highervoltage side with Vss being a reference.

[5.9] Ninth Modification

In each of the above-described embodiments, the shift from theindication mode to the power saving mode is made upon detecting thestate where the timepiece is carried by the user. However, the presentinvention is not limited to those embodiments, the shift from theindication mode to the power saving mode may be executed in accordancewith an instruction from the user.

For example, manipulation of a button, a crown or the like arranged onan outer case of the timepiece 1 may be detected to shift the mode fromthe indication mode to the power saving mode in accordance with adetection result.

In this case, since the mode can be shifted to the power saving mode atonce upon intentional manipulation of the user, power saving is alsoachievable when the user is just wearing the timepiece with no need ofknowing the indicated time. As a result, power consumption can befurther reduced, and the timepiece can keep the precise time for alonger period of time.

[5.10] Tenth Modification

While the power supply unit B performs half-wave rectification of the ACvoltage supplied from the power generation unit A in each of theabove-described embodiments, the present invention is not limited tothose embodiments. Of course, the power supply unit B may performfull-wave rectification.

[5.11] Eleventh Modification

The above description has been made in connection with only electronicequipment having power generators. For another type of electronicequipment not having a power generator but a power supply unit, e.g., aprimary battery, capable of accumulating electric energy, however, theelectronic equipment can be constructed so as to detect whether it iscarried by the user, and to effect the shift to the power saving mode orthe shift from the power saving mode to the normal operating mode.

INDUSTRIAL APPLICABILITY

As described hereinabove, the portable electronic equipment of thepresent invention includes a carried-by-user detector for detectingwhether the electronic equipment is in a state carried by the user ornot. When the electronic equipment is in a state not carried by theuser, i.e., when the user is not employing the electronic equipment, theoperating mode is shifted from the normal operating mode to the powersaving mode to reduce power consumption of the electronic equipment.

Accordingly, useless consumption of power during non-use of theelectronic equipment can be reduced.

Further, the electronic equipment of the present invention includes apower generator for generating power by converting first energy(=kinetic energy, thermal energy, pressure, optical energy orelectromagnetic wave energy) into electric energy as second energy, anda carried-by-user detector for detecting whether the electronicequipment is in a state carried by the user. The operating mode isshifted between the power saving mode and the normal operating mode (theindication mode in the above embodiments) depending on a powergeneration state or in combination with the state carried with the user.

Therefore, at least when the power generator is not in the state ofgenerating power, the operation of the electronic equipment is stoppedto cut back on useless consumption of power. Moreover, if the electronicequipment is not in the state carried by the user even with the powergenerator being in the state of generating power, the operating mode isshifted to the power saving mode and power consumption is furtherreduced.

Also, the timepiece as one form of the electronic equipment of thepresent invention includes a power generator capable of converting firstenergy (=kinetic energy, thermal energy, pressure, optical energy orelectromagnetic wave energy) into electric energy as second energy. Thetimepiece determines whether the timepiece is carried by the user or notbased on whether the power generator is generating power or not, ordetermines whether the timepiece is carried by the user or not by usingany of various carried-state detecting sensors such as an accelerationsensor. When the timepiece is carried by the user, the operating mode isalways set to the indication mode in which the time is indicated. Whenthe timepiece is not carried by the user, the time indication is stoppedto save energy if the condition that a predeterminednon-power-generation time has elapsed is satisfied.

Accordingly, even in the night or the winter, the timepiece as one formof the electronic equipment of the present invention can indicate thetime whenever the user is wearing the timepiece and wants to see thetime, thereby keeping the user from feeling inconvenienced. On the otherhand, when the timepiece is not carried by the user and there is nochance for the user to see the time, the indication is stopped even withlight surroundings, whereby energy can be saved. As a result, it ispossible to provide the electronic equipment (timepiece) and the controlmethod for the same with which the time can be indicated with goodaccuracy for a long time without using any battery and withoutinconveniencing the user.

What is claimed is:
 1. Portable electronic equipment comprising: a powersupply device capable of accumulating electric energy, a driven devicedriven with electric power supplied from said power supply device, acarrying-on-user detector for detecting whether said electronicequipment is in a state carried with a user or not, and a mode shiftcontrol device for shifting an operating mode of said driven device froma normal operating mode to a power saving mode in accordance with adetection result of said carrying-on-user detector when said electronicequipment is in a state not carried with the user, for thereby reducingpower consumption of said driven device, and wherein said power supplydevice includes a power generator for generating electric power byconverting first energy into the electric energy as second energy, andsaid power supply device is able to accumulate the generated power, andwherein said carrying-on-user detector detects whether said electronicequipment is in the state carried with the user or not in accordancewith a power generation state of said power generator.
 2. Electronicequipment according to claim 1, further comprising: an operatingcondition restoring device for, when the operating mode is restored tothe normal operating mode again after a shift to the power saving mode,restoring an operating condition of said driven device to the sameoperating condition as resulted in the case of operating said drivendevice continuously for a period of time elapsed from the shift to thepower saving mode to the time of restoring to the normal operating mode.3. Electronic equipment according to claim 2, wherein: said mode shiftcontrol device shifts the operating mode to the power saving mode whenan amount of power accumulated in said power supply device is not lessthan a predetermined amount of power which is set beforehand andcorresponds to the amount of power for said restoring of the operatingcondition.
 4. Electronic equipment according to claim 2, wherein: saidcarrying-on-user detector detects the carried state of said electronicequipment based on an electromotive voltage produced in said powergenerator.
 5. Electronic equipment according to claim 4, wherein: saidcarrying-on-user detector compares an electromotive voltage produced insaid power generator with a plurality of setting voltage values, anddetects the carried state of said electronic equipment in accordancewith a comparison result.
 6. Electronic equipment according to claim 5,wherein: said carrying-on-user detector detects the carried state ofsaid electronic equipment by selecting one of said plurality of settingvoltage values depending on the current mode, and comparing theelectromotive voltage produced in said power generator with the selectedsetting voltage value.
 7. Electronic equipment according to claim 6,wherein: said carrying-on-user detector sets the setting voltage value,which is used for determining whether said operating mode is to beshifted from the power saving mode to the normal operating mode, to behigher than the setting voltage value used for determining whether saidoperating mode is to be shifted from the normal operating mode to thepower saving mode.
 8. Electronic equipment according to claim 1,wherein: said carrying-on-user detector detects the carried state ofsaid electronic equipment based on a charging current in said powersupply device.
 9. Electronic equipment according to claim 8, wherein:said carrying-on-user detector compares the charging current in saidpower supply device with a plurality of setting current values, anddetects the carried state of said electronic equipment in accordancewith a comparison result.
 10. Electronic equipment according to claim 9,wherein: said carrying-on-user detector detects the carried state ofsaid electronic equipment by selecting one of said plurality of settingcurrent values depending on the current mode, and comparing the chargingcurrent in said power supply device with the selected setting currentvalue.
 11. Electronic equipment according to claim 10, wherein: saidcarrying-on-user detector sets the setting current value, which is usedfor the mode shift from the power saving mode to the normal operatingmode, to be higher than the setting current value used for the shiftfrom the normal operating mode to the power saving mode.
 12. Electronicequipment according to claim 1, wherein: said carrying-on-user detectordetects the carried state of said electronic equipment based on a powergeneration duration time of said power generator.
 13. Electronicequipment according to claim 12, wherein: said carrying-on-user detectorcompares the power generation duration time of said power generator witha plurality of setting time values, and detects the carried state ofsaid electronic equipment in accordance with a comparison result. 14.Electronic equipment according to claim 13, wherein: saidcarrying-on-user detector detects the carried state of said electronicequipment by selecting one of said plurality of setting time valuesdepending on the current mode, and comparing the power generationduration time of said power generator with the s elected set ting timevalue.
 15. Electronic equipment according to claim 14, wherein: saidcarrying-on-user detector sets the setting time value, which is used forthe mode shift from the power saving mode to the normal operating mode,to be longer than the setting time value used for the shift from thenormal operating mode to the power saving mode.
 16. Electronic equipmentaccording to claim 1, wherein: said carrying-on-user detector detectsthe carried state of said electronic equipment based frequency of thepower generated by said power generator.
 17. Electronic equipmentaccording to claim 16, wherein: said carrying-on-user detector detectsthe frequency of the power generated by said power generator by countingthe number of peaks of an electromotive voltage produced in said powergenerator during a period until a setting time elapses from a point intime at which the electromotive voltage has exceeded a setting voltagevalue.
 18. Electronic equipment according to claim 16, wherein: saidcarrying-on-user detector compares the frequency of the power generatedby said power generator with a plurality of setting frequency values,and detects the carried state of said electronic equipment in accordancewith a comparison result.
 19. Electronic equipment according to claim18, wherein: said carrying-on-user detector detects the carried state ofsaid electronic equipment by selecting one of said plurality of settingfrequency values depending on the current mode, and comparing thefrequency of the power generated by said power generator with theselected setting frequency value.
 20. Electronic equipment according toclaim 19, wherein: said carrying-on-user detector sets the settingfrequency value, which is used for determining whether said operatingmode is to be shifted from the power saving mode to the normal operatingmode, to be higher than the setting frequency value used for determiningwhether said operating mode is to be shifted from the normal operatingmode to the power saving mode.
 21. Electronic equipment according toclaim 1, wherein: said power generator includes a plurality of auxiliarypower generators for converting said first energy in different forms.22. Electronic equipment according to claim 1, wherein: said firstenergy is any of kinetic energy, pressure energy or thermal energy. 23.Electronic equipment according to claim 1, wherein: said power generatorgenerates AC electric power by converting kinetic energy as said firstenergy into electric energy, and said power supply device rectifies andaccumulates the generated AC power.
 24. Electronic equipment accordingto claim 23, wherein: said carrying-on-user detector comprises switchingmeans being switched over in accordance with a cycle of the AC powergenerated by said power generator, a capacity element for accumulatingelectric charges in accordance with the switching operation of saidswitching means, discharge means inserted in a discharge path of saidcapacity element and discharging the electric charges accumulated insaid capacity element, a measuring portion for counting said powergeneration duration time by measuring a period of time during which avoltage across said capacity element exceeds a predetermined value, anda carrying-on-user detecting portion for detecting the carried state ofsaid electronic equipment based on said power generation duration time.25. Electronic equipment according to claim 23, wherein: saidcarrying-on-user detector detects the carried state of said electronicequipment based on the frequency of the power generated by said powergenerator.
 26. Electronic equipment according to claim 25, wherein: saidcarrying-on-user detector detects the frequency of the power generatedby said power generator by counting the number of peaks of anelectromotive voltage produced in said power generator during a perioduntil a setting time elapses from a point in time at which theelectromotive voltage has exceeded a setting voltage value. 27.Electronic equipment according to claim 25, wherein: saidcarrying-on-user detector compares the frequency of the power generatedby said power generator with a plurality of setting frequency values,and detects the carried state of said electronic equipment in accordancewith a comparison result.
 28. Electronic equipment according to claim27, wherein: said carrying-on-user detector detects the carried state ofsaid electronic equipment by selecting one of said plurality of settingfrequency values depending on the current mode, and comparing thefrequency of the power generated by said power generator with theselected setting frequency value.
 29. Electronic equipment according toclaim 23, wherein: said power generator comprises a rotating weightundergoing swing motion, and a power generation element for generatingelectromotive forces with the rotary motion of said rotating weight. 30.Electronic equipment according to claim 23, wherein: said powergenerator comprises a resilient member to which deformation forces areapplied, rotating means undergoing rotary motion due to restoring forcesdeveloped by said resilient member going to restore to an originalshape, and a power generation element for generating electromotiveforces with the rotary motion of said rotating means.
 31. Electronicequipment according to claim 23, wherein: said power generator comprisesa piezoelectric device for generating electromotive forces with thepiezoelectric effect when subjected to a displacement.
 32. Electronicequipment according to claim 1, wherein: said driven device is a timeindicating device for indicating the time with the electric powersupplied from said power supply device, and said mode shift controldevice shifts the operating mode of said time indicating device to thepower saving mode in accordance with a power generation state of saidpower generator, for thereby reducing power consumption of said timeindicating device.
 33. Electronic equipment according to claim 32,further comprising: a time indication restoring device for, when theoperating mode is restored to a time indication mode as the normaloperating mode again after a shift to the power saving mode, restoring atime indicative condition of said time indicating device to the sametime indicative condition as resulted in the case of operating said timeindicating device continuously for a period of time elapsed from theshift to the power saving mode to the time of restoring to the timeindication mode.
 34. Electronic equipment according to claim 32,wherein: the power saving mode stops the time indication in said timeindicating device.
 35. Electronic equipment according to claim 32,wherein: said time indicating device comprises an hour- and minute-handdriving device for driving hour and minute hands, and a second handdriving device for driving a second hand, and the power saving modecomprises a first power saving mode in which operation of said secondhand driving device is stopped, and a second power saving mode in whichoperations of said hour- and minute-hand driving device and said secondhand driving device are stopped.
 36. Electronic equipment according toclaim 32, wherein: said time indicating device is an analog indicatingdevice for mechanically driving analog hands to rotate said hands, andsaid mode shift control device comprises a power-saving-mode timestorage for storing a power-saving-mode duration time during which thepower saving mode is continued, and a time restoring portion forrestoring the time indication of said analog indicating device based onthe power-saving-mode duration time when the operating mode is shiftedfrom the power saving mode to the indication mode.
 37. Electronicequipment according to claim 32, wherein: said mode shift control devicehas a mode setting function capable of selectively setting one of thepower saving mode in which the time indication of said time indicatingdevice is stopped in accordance with the power generation state of thepower generator, and the indication mode in which the time is indicated.38. Portable electronic equipment comprising: a power supply devicecapable of accumulating electric energy, a driven device driven withelectric power supplied from said power supply device, acarrying-on-user detector for detecting whether said electronicequipment is in a state carried with a user or not, and a mode shiftcontrol device for shifting an operating mode of said driven device froma normal operating mode to a power saving mode in accordance with adetection result of said carrying-on-user detector when said electronicequipment is in a state not carried with the user, for thereby reducingpower consumption of said driven device, and wherein said power supplydevice includes a power generator for generating electric power byconverting first energy into the electric energy as second energy, andsaid power supply device is able to accumulate the generated power, andwherein said mode shift control device shifts the operating mode of saiddriven device to the power saving mode when said electronic equipment isin the not carried state and the power generation state of said powergenerator is in a predetermined power generation state which is setbeforehand and corresponds to the power saving mode.
 39. Electronicequipment according to claim 38, wherein: said carrying-on-user detectorincludes an acceleration sensor for detecting acceleration generatedwhen said electronic equipment is carried with the user.
 40. Electronicequipment according to claim 38, wherein: said carrying-on-user detectordetects the carried state of said electronic equipment by detecting achange in electrode-to-electrode resistance value orelectrode-to-electrode capacitance value occurring when said electronicequipment is carried with the user.
 41. Electronic equipment accordingto claim 38, wherein: said carrying-on-user detector includes a switchportion turning into an on- or off-state when said electronic equipmentis carried with the user, and detects the carried state of saidelectronic equipment in accordance with the on/off state of said switchportion.
 42. A control method for electronic equipment comprising apower supply device capable of accumulating electric energy, and adriven device driven with electric power supplied from said power supplydevice, said control method comprising: a carrying-on-user detectingstep of detecting whether said electronic equipment is in a statecarried with a user or not, and a mode shift control step of shifting anoperating mode of said driven device from a normal operating mode to apower saving mode in accordance with a result of the detection when saidelectronic equipment is in a state not carried with the user, forthereby reducing power consumption of said driven device, and whereinsaid power supply device includes a power generator for generatingelectric power by converting first energy into the electric energy assecond energy, and said carrying-on-user detecting step detects whethersaid electronic equipment is in the state carried with the user or notin accordance with a power generation state of said power generator. 43.A control method for electronic equipment according to claim 42, furthercomprising: an operating condition restoring step of, when the operatingmode is restored to the normal operating mode again after a shift to thepower saving mode, restoring an operating condition of said drivendevice to the same operating condition as resulted in the case ofoperating said driven device continuously for a period of time elapsedfrom the shift to the power saving mode to the time of restoring to thenormal operating mode.
 44. A control method for electronic equipmentaccording to claim 43, wherein: said mode shift control step shifts theoperating mode to the power saving mode when an amount of poweraccumulated in said power supply device is not less than a predeterminedamount of power which is set beforehand and corresponds to the amount ofpower for said restoring of the operating condition.
 45. A controlmethod for electronic equipment according to claim 42, wherein: saiddriven device is a time indicating device for indicating the time withthe electric power supplied from said power supply device, and saidnormal operating mode is an indication mode causing said time indicatingdevice to indicate the time.
 46. A control method for electronicequipment according to claim 42, wherein: said first energy is any ofkinetic energy, pressure energy or thermal energy.
 47. A control methodfor electronic equipment according to claim 42, wherein: said firstenergy is optical energy, and said mode shift control step includes thecarrying-on-user detecting step of detecting whether said electronicequipment is in the state carried with the user or not, and shifts theoperating mode of said driven device to the power saving mode when saidelectronic equipment is in the not-carried state and the powergeneration state of said power generator is in a predetermined powergeneration state which is set beforehand and corresponds to the powersaving mode.
 48. A control method for electronic equipment comprising apower supply device capable of accumulating electric energy, and a timeindicating device capable of indicating the time with electric powersupplied from said power supply device, said control method comprising:a carrying-on-user detecting step of detecting whether said electronicequipment is in a state carried with a user or not, and a mode shiftcontrol step of shifting an operating mode of said time indicatingdevice from a normal operating mode to a power saving mode in accordancewith a detection result in said carrying-on-user detecting step whensaid electronic equipment is in a state not carried with the user, forthereby reducing power consumption of said time indicating device, andwherein said power supply device includes a power generator forgenerating electric power by converting first energy into the electricenergy as second energy, and said carrying-on-user detecting stepdetects whether said electronic equipment is in the state carried withthe user or not in accordance with a power generation state of saidpower generator.
 49. A control method for electronic equipment accordingto claim 48,further comprising: a time indication restoring step of,when the operating mode is restored to the normal operating mode againafter a shift to the power saving mode, restoring a time indicativecondition of said time indicating device to the same time indicativecondition as resulted in the case of operating said time indicatingdevice continuously for a period of time elapsed from the shift to thepower saving mode to the time of restoring to the normal operating mode.50. A control method for electronic equipment according to claim 49,wherein: said mode shift control step shifts the operating mode to thepower saving mode when an amount of power accumulated in said powersupply device is not less than a predetermined amount of power which isset beforehand and corresponds to the amount of power for said restoringof the operating condition.
 51. A control method for electronicequipment according to claim 48, wherein: said mode shift control stepincludes a power-generation-state determining step of determiningwhether said power generator is in a state of generating power or notbased on whether an electromotive voltage of said power generator ishigher than a setting voltage set beforehand, and shifts the operatingmode from the power saving mode to an indication mode, in which the timeis indicated, in accordance with a result of the determination when saidpower generator is brought into the state of generating power.
 52. Acontrol method for electronic equipment according to claim 48, wherein:said mode shift control step includes a power-generation-statedetermining step of determining whether said power generator is in astate of generating power or not based on whether a power generationduration time of said power generator is longer than a setting time setbeforehand, and shifts the operating mode from the power saving mode toan indication mode, in which the time is indicated, in accordance with aresult of the determination when said power generator is brought intothe state of generating power.
 53. A control method for electronicequipment according to claim 48, wherein: the power saving mode stopsthe time indication in said time indicating device.
 54. A control methodfor electronic equipment according to claim 48, wherein: said timeindicating device comprises an hour- and minute-hand driving device fordriving hour and minute hands, and a second hand driving device fordriving a second hand, and the power saving mode comprises a first powersaving mode in which operation of said second hand driving device isstopped, and a second power saving mode in which operations of saidhour- and minute-hand driving device and said second hand driving deviceare stopped.
 55. A control method for electronic equipment comprising apower supply device capable of accumulating electric energy, and adriven device driven with electric power supplied from said power supplydevice, said control method comprising: a carrying-on-user detectingstep of detecting whether said electronic equipment is in a statecarried with a user or not, and a mode shift control step of shifting anoperating mode of said driven device from a normal operating mode to apower saving mode in accordance with a result of the detection when saidelectronic equipment is in a state not carried with the user, forthereby reducing power consumption of said driven device, and whereinsaid power supply device includes a power generator for generatingelectric power by converting first energy into the electric energy assecond energy, and said mode shift control step includes shifting theoperating mode of said driven device to the power saving mode when saidelectronic equipment is in the not-carried state and the powergeneration state of said power generator is in a predetermined powergeneration state which is set beforehand and corresponds to the powersaving mode.